pefiphery.sol

// Sources flattened with buidler v1.4.8 https://buidler.dev

// File @uniswap/v2-core/contracts/interfaces/IUniswapV2Callee.sol@v1.0.1

pragma solidity >=0.5.0;

interface IUniswapV2Callee {
    function uniswapV2Call(address sender, uint amount0, uint amount1, bytes calldata data) external;
}


// File @uniswap/v2-core/contracts/interfaces/IUniswapV2Pair.sol@v1.0.1

pragma solidity >=0.5.0;

interface IUniswapV2Pair {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external pure returns (string memory);
    function symbol() external pure returns (string memory);
    function decimals() external pure returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);

    function DOMAIN_SEPARATOR() external view returns (bytes32);
    function PERMIT_TYPEHASH() external pure returns (bytes32);
    function nonces(address owner) external view returns (uint);

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;

    event Mint(address indexed sender, uint amount0, uint amount1);
    event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
    event Swap(
        address indexed sender,
        uint amount0In,
        uint amount1In,
        uint amount0Out,
        uint amount1Out,
        address indexed to
    );
    event Sync(uint112 reserve0, uint112 reserve1);

    function MINIMUM_LIQUIDITY() external pure returns (uint);
    function factory() external view returns (address);
    function token0() external view returns (address);
    function token1() external view returns (address);
    function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
    function price0CumulativeLast() external view returns (uint);
    function price1CumulativeLast() external view returns (uint);
    function kLast() external view returns (uint);

    function mint(address to) external returns (uint liquidity);
    function burn(address to) external returns (uint amount0, uint amount1);
    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
    function skim(address to) external;
    function sync() external;

    function initialize(address, address) external;
}


// File contracts/libraries/SafeMath.sol

pragma solidity =0.6.6;

// a library for performing overflow-safe math, courtesy of DappHub (https://github.com/dapphub/ds-math)

library SafeMath {
    function add(uint x, uint y) internal pure returns (uint z) {
        require((z = x + y) >= x, 'ds-math-add-overflow');
    }

    function sub(uint x, uint y) internal pure returns (uint z) {
        require((z = x - y) <= x, 'ds-math-sub-underflow');
    }

    function mul(uint x, uint y) internal pure returns (uint z) {
        require(y == 0 || (z = x * y) / y == x, 'ds-math-mul-overflow');
    }
}


// File contracts/libraries/PancakeLibrary.sol

pragma solidity >=0.5.0;

library PancakeLibrary {
    using SafeMath for uint;

    // returns sorted token addresses, used to handle return values from pairs sorted in this order
    function sortTokens(address tokenA, address tokenB) internal pure returns (address token0, address token1) {
        require(tokenA != tokenB, 'PancakeLibrary: IDENTICAL_ADDRESSES');
        (token0, token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);
        require(token0 != address(0), 'PancakeLibrary: ZERO_ADDRESS');
    }

    // calculates the CREATE2 address for a pair without making any external calls
    function pairFor(address factory, address tokenA, address tokenB) internal pure returns (address pair) {
        (address token0, address token1) = sortTokens(tokenA, tokenB);
        pair = address(uint(keccak256(abi.encodePacked(
                hex'ff',
                factory,
                keccak256(abi.encodePacked(token0, token1)),
                hex'd0d4c4cd0848c93cb4fd1f498d7013ee6bfb25783ea21593d5834f5d250ece66' // init code hash
            ))));
    }

    // fetches and sorts the reserves for a pair
    function getReserves(address factory, address tokenA, address tokenB) internal view returns (uint reserveA, uint reserveB) {
        (address token0,) = sortTokens(tokenA, tokenB);
        pairFor(factory, tokenA, tokenB);
        (uint reserve0, uint reserve1,) = IUniswapV2Pair(pairFor(factory, tokenA, tokenB)).getReserves();
        (reserveA, reserveB) = tokenA == token0 ? (reserve0, reserve1) : (reserve1, reserve0);
    }

    // given some amount of an asset and pair reserves, returns an equivalent amount of the other asset
    function quote(uint amountA, uint reserveA, uint reserveB) internal pure returns (uint amountB) {
        require(amountA > 0, 'PancakeLibrary: INSUFFICIENT_AMOUNT');
        require(reserveA > 0 && reserveB > 0, 'PancakeLibrary: INSUFFICIENT_LIQUIDITY');
        amountB = amountA.mul(reserveB) / reserveA;
    }

    // given an input amount of an asset and pair reserves, returns the maximum output amount of the other asset
    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) internal pure returns (uint amountOut) {
        require(amountIn > 0, 'PancakeLibrary: INSUFFICIENT_INPUT_AMOUNT');
        require(reserveIn > 0 && reserveOut > 0, 'PancakeLibrary: INSUFFICIENT_LIQUIDITY');
        uint amountInWithFee = amountIn.mul(998);
        uint numerator = amountInWithFee.mul(reserveOut);
        uint denominator = reserveIn.mul(1000).add(amountInWithFee);
        amountOut = numerator / denominator;
    }

    // given an output amount of an asset and pair reserves, returns a required input amount of the other asset
    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) internal pure returns (uint amountIn) {
        require(amountOut > 0, 'PancakeLibrary: INSUFFICIENT_OUTPUT_AMOUNT');
        require(reserveIn > 0 && reserveOut > 0, 'PancakeLibrary: INSUFFICIENT_LIQUIDITY');
        uint numerator = reserveIn.mul(amountOut).mul(1000);
        uint denominator = reserveOut.sub(amountOut).mul(998);
        amountIn = (numerator / denominator).add(1);
    }

    // performs chained getAmountOut calculations on any number of pairs
    function getAmountsOut(address factory, uint amountIn, address[] memory path) internal view returns (uint[] memory amounts) {
        require(path.length >= 2, 'PancakeLibrary: INVALID_PATH');
        amounts = new uint[](path.length);
        amounts[0] = amountIn;
        for (uint i; i < path.length - 1; i++) {
            (uint reserveIn, uint reserveOut) = getReserves(factory, path[i], path[i + 1]);
            amounts[i + 1] = getAmountOut(amounts[i], reserveIn, reserveOut);
        }
    }

    // performs chained getAmountIn calculations on any number of pairs
    function getAmountsIn(address factory, uint amountOut, address[] memory path) internal view returns (uint[] memory amounts) {
        require(path.length >= 2, 'PancakeLibrary: INVALID_PATH');
        amounts = new uint[](path.length);
        amounts[amounts.length - 1] = amountOut;
        for (uint i = path.length - 1; i > 0; i--) {
            (uint reserveIn, uint reserveOut) = getReserves(factory, path[i - 1], path[i]);
            amounts[i - 1] = getAmountIn(amounts[i], reserveIn, reserveOut);
        }
    }
}


// File contracts/interfaces/V1/IUniswapV1Factory.sol

pragma solidity >=0.5.0;

interface IUniswapV1Factory {
    function getExchange(address) external view returns (address);
}


// File contracts/interfaces/V1/IUniswapV1Exchange.sol

pragma solidity >=0.5.0;

interface IUniswapV1Exchange {
    function balanceOf(address owner) external view returns (uint);
    function transferFrom(address from, address to, uint value) external returns (bool);
    function removeLiquidity(uint, uint, uint, uint) external returns (uint, uint);
    function tokenToEthSwapInput(uint, uint, uint) external returns (uint);
    function ethToTokenSwapInput(uint, uint) external payable returns (uint);
}


// File contracts/interfaces/IPancakeRouter01.sol

pragma solidity >=0.6.2;

interface IPancakeRouter01 {
    function factory() external pure returns (address);
    function WETH() external pure returns (address);

    function addLiquidity(
        address tokenA,
        address tokenB,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB, uint liquidity);
    function addLiquidityETH(
        address token,
        uint amountTokenDesired,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external payable returns (uint amountToken, uint amountETH, uint liquidity);
    function removeLiquidity(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETH(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountToken, uint amountETH);
    function removeLiquidityWithPermit(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETHWithPermit(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountToken, uint amountETH);
    function swapExactTokensForTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapTokensForExactTokens(
        uint amountOut,
        uint amountInMax,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);
    function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);

    function quote(uint amountA, uint reserveA, uint reserveB) external pure returns (uint amountB);
    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) external pure returns (uint amountOut);
    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) external pure returns (uint amountIn);
    function getAmountsOut(uint amountIn, address[] calldata path) external view returns (uint[] memory amounts);
    function getAmountsIn(uint amountOut, address[] calldata path) external view returns (uint[] memory amounts);
}


// File contracts/interfaces/IERC20.sol

pragma solidity >=0.5.0;

interface IERC20 {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external view returns (string memory);
    function symbol() external view returns (string memory);
    function decimals() external view returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);
}


// File contracts/interfaces/IWETH.sol

pragma solidity >=0.5.0;

interface IWETH {
    function deposit() external payable;
    function transfer(address to, uint value) external returns (bool);
    function withdraw(uint) external;
}


// File contracts/examples/ExampleFlashSwap.sol

pragma solidity =0.6.6;






contract ExampleFlashSwap is IUniswapV2Callee {
    IUniswapV1Factory immutable factoryV1;
    address immutable factory;
    IWETH immutable WETH;

    constructor(address _factory, address _factoryV1, address router) public {
        factoryV1 = IUniswapV1Factory(_factoryV1);
        factory = _factory;
        WETH = IWETH(IPancakeRouter01(router).WETH());
    }

    // needs to accept ETH from any V1 exchange and WETH. ideally this could be enforced, as in the router,
    // but it's not possible because it requires a call to the v1 factory, which takes too much gas
    receive() external payable {}

    // gets tokens/WETH via a V2 flash swap, swaps for the ETH/tokens on V1, repays V2, and keeps the rest!
    function uniswapV2Call(address sender, uint amount0, uint amount1, bytes calldata data) external override {
        address[] memory path = new address[](2);
        uint amountToken;
        uint amountETH;
        { // scope for token{0,1}, avoids stack too deep errors
        address token0 = IUniswapV2Pair(msg.sender).token0();
        address token1 = IUniswapV2Pair(msg.sender).token1();
        assert(msg.sender == PancakeLibrary.pairFor(factory, token0, token1)); // ensure that msg.sender is actually a V2 pair
        assert(amount0 == 0 || amount1 == 0); // this strategy is unidirectional
        path[0] = amount0 == 0 ? token0 : token1;
        path[1] = amount0 == 0 ? token1 : token0;
        amountToken = token0 == address(WETH) ? amount1 : amount0;
        amountETH = token0 == address(WETH) ? amount0 : amount1;
        }

        assert(path[0] == address(WETH) || path[1] == address(WETH)); // this strategy only works with a V2 WETH pair
        IERC20 token = IERC20(path[0] == address(WETH) ? path[1] : path[0]);
        IUniswapV1Exchange exchangeV1 = IUniswapV1Exchange(factoryV1.getExchange(address(token))); // get V1 exchange

        if (amountToken > 0) {
            (uint minETH) = abi.decode(data, (uint)); // slippage parameter for V1, passed in by caller
            token.approve(address(exchangeV1), amountToken);
            uint amountReceived = exchangeV1.tokenToEthSwapInput(amountToken, minETH, uint(-1));
            uint amountRequired = PancakeLibrary.getAmountsIn(factory, amountToken, path)[0];
            assert(amountReceived > amountRequired); // fail if we didn't get enough ETH back to repay our flash loan
            WETH.deposit{value: amountRequired}();
            assert(WETH.transfer(msg.sender, amountRequired)); // return WETH to V2 pair
            (bool success,) = sender.call{value: amountReceived - amountRequired}(new bytes(0)); // keep the rest! (ETH)
            assert(success);
        } else {
            (uint minTokens) = abi.decode(data, (uint)); // slippage parameter for V1, passed in by caller
            WETH.withdraw(amountETH);
            uint amountReceived = exchangeV1.ethToTokenSwapInput{value: amountETH}(minTokens, uint(-1));
            uint amountRequired = PancakeLibrary.getAmountsIn(factory, amountETH, path)[0];
            assert(amountReceived > amountRequired); // fail if we didn't get enough tokens back to repay our flash loan
            assert(token.transfer(msg.sender, amountRequired)); // return tokens to V2 pair
            assert(token.transfer(sender, amountReceived - amountRequired)); // keep the rest! (tokens)
        }
    }
}


// File @uniswap/v2-core/contracts/interfaces/IUniswapV2Factory.sol@v1.0.1

pragma solidity >=0.5.0;

interface IUniswapV2Factory {
    event PairCreated(address indexed token0, address indexed token1, address pair, uint);

    function feeTo() external view returns (address);
    function feeToSetter() external view returns (address);

    function getPair(address tokenA, address tokenB) external view returns (address pair);
    function allPairs(uint) external view returns (address pair);
    function allPairsLength() external view returns (uint);

    function createPair(address tokenA, address tokenB) external returns (address pair);

    function setFeeTo(address) external;
    function setFeeToSetter(address) external;
}


// File @uniswap/lib/contracts/libraries/FixedPoint.sol@v1.1.1

pragma solidity >=0.4.0;

// a library for handling binary fixed point numbers (https://en.wikipedia.org/wiki/Q_(number_format))
library FixedPoint {
    // range: [0, 2**112 - 1]
    // resolution: 1 / 2**112
    struct uq112x112 {
        uint224 _x;
    }

    // range: [0, 2**144 - 1]
    // resolution: 1 / 2**112
    struct uq144x112 {
        uint _x;
    }

    uint8 private constant RESOLUTION = 112;

    // encode a uint112 as a UQ112x112
    function encode(uint112 x) internal pure returns (uq112x112 memory) {
        return uq112x112(uint224(x) << RESOLUTION);
    }

    // encodes a uint144 as a UQ144x112
    function encode144(uint144 x) internal pure returns (uq144x112 memory) {
        return uq144x112(uint256(x) << RESOLUTION);
    }

    // divide a UQ112x112 by a uint112, returning a UQ112x112
    function div(uq112x112 memory self, uint112 x) internal pure returns (uq112x112 memory) {
        require(x != 0, 'FixedPoint: DIV_BY_ZERO');
        return uq112x112(self._x / uint224(x));
    }

    // multiply a UQ112x112 by a uint, returning a UQ144x112
    // reverts on overflow
    function mul(uq112x112 memory self, uint y) internal pure returns (uq144x112 memory) {
        uint z;
        require(y == 0 || (z = uint(self._x) * y) / y == uint(self._x), "FixedPoint: MULTIPLICATION_OVERFLOW");
        return uq144x112(z);
    }

    // returns a UQ112x112 which represents the ratio of the numerator to the denominator
    // equivalent to encode(numerator).div(denominator)
    function fraction(uint112 numerator, uint112 denominator) internal pure returns (uq112x112 memory) {
        require(denominator > 0, "FixedPoint: DIV_BY_ZERO");
        return uq112x112((uint224(numerator) << RESOLUTION) / denominator);
    }

    // decode a UQ112x112 into a uint112 by truncating after the radix point
    function decode(uq112x112 memory self) internal pure returns (uint112) {
        return uint112(self._x >> RESOLUTION);
    }

    // decode a UQ144x112 into a uint144 by truncating after the radix point
    function decode144(uq144x112 memory self) internal pure returns (uint144) {
        return uint144(self._x >> RESOLUTION);
    }
}


// File contracts/libraries/PancakeOracleLibrary.sol

pragma solidity >=0.5.0;


// library with helper methods for oracles that are concerned with computing average prices
library PancakeOracleLibrary {
    using FixedPoint for *;

    // helper function that returns the current block timestamp within the range of uint32, i.e. [0, 2**32 - 1]
    function currentBlockTimestamp() internal view returns (uint32) {
        return uint32(block.timestamp % 2 ** 32);
    }

    // produces the cumulative price using counterfactuals to save gas and avoid a call to sync.
    function currentCumulativePrices(
        address pair
    ) internal view returns (uint price0Cumulative, uint price1Cumulative, uint32 blockTimestamp) {
        blockTimestamp = currentBlockTimestamp();
        price0Cumulative = IUniswapV2Pair(pair).price0CumulativeLast();
        price1Cumulative = IUniswapV2Pair(pair).price1CumulativeLast();

        // if time has elapsed since the last update on the pair, mock the accumulated price values
        (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast) = IUniswapV2Pair(pair).getReserves();
        if (blockTimestampLast != blockTimestamp) {
            // subtraction overflow is desired
            uint32 timeElapsed = blockTimestamp - blockTimestampLast;
            // addition overflow is desired
            // counterfactual
            price0Cumulative += uint(FixedPoint.fraction(reserve1, reserve0)._x) * timeElapsed;
            // counterfactual
            price1Cumulative += uint(FixedPoint.fraction(reserve0, reserve1)._x) * timeElapsed;
        }
    }
}


// File contracts/examples/ExampleOracleSimple.sol

pragma solidity =0.6.6;




// fixed window oracle that recomputes the average price for the entire period once every period
// note that the price average is only guaranteed to be over at least 1 period, but may be over a longer period
contract ExampleOracleSimple {
    using FixedPoint for *;

    uint public constant PERIOD = 24 hours;

    IUniswapV2Pair immutable pair;
    address public immutable token0;
    address public immutable token1;

    uint    public price0CumulativeLast;
    uint    public price1CumulativeLast;
    uint32  public blockTimestampLast;
    FixedPoint.uq112x112 public price0Average;
    FixedPoint.uq112x112 public price1Average;

    constructor(address factory, address tokenA, address tokenB) public {
        IUniswapV2Pair _pair = IUniswapV2Pair(PancakeLibrary.pairFor(factory, tokenA, tokenB));
        pair = _pair;
        token0 = _pair.token0();
        token1 = _pair.token1();
        price0CumulativeLast = _pair.price0CumulativeLast(); // fetch the current accumulated price value (1 / 0)
        price1CumulativeLast = _pair.price1CumulativeLast(); // fetch the current accumulated price value (0 / 1)
        uint112 reserve0;
        uint112 reserve1;
        (reserve0, reserve1, blockTimestampLast) = _pair.getReserves();
        require(reserve0 != 0 && reserve1 != 0, 'ExampleOracleSimple: NO_RESERVES'); // ensure that there's liquidity in the pair
    }

    function update() external {
        (uint price0Cumulative, uint price1Cumulative, uint32 blockTimestamp) =
            PancakeOracleLibrary.currentCumulativePrices(address(pair));
        uint32 timeElapsed = blockTimestamp - blockTimestampLast; // overflow is desired

        // ensure that at least one full period has passed since the last update
        require(timeElapsed >= PERIOD, 'ExampleOracleSimple: PERIOD_NOT_ELAPSED');

        // overflow is desired, casting never truncates
        // cumulative price is in (uq112x112 price * seconds) units so we simply wrap it after division by time elapsed
        price0Average = FixedPoint.uq112x112(uint224((price0Cumulative - price0CumulativeLast) / timeElapsed));
        price1Average = FixedPoint.uq112x112(uint224((price1Cumulative - price1CumulativeLast) / timeElapsed));

        price0CumulativeLast = price0Cumulative;
        price1CumulativeLast = price1Cumulative;
        blockTimestampLast = blockTimestamp;
    }

    // note this will always return 0 before update has been called successfully for the first time.
    function consult(address token, uint amountIn) external view returns (uint amountOut) {
        if (token == token0) {
            amountOut = price0Average.mul(amountIn).decode144();
        } else {
            require(token == token1, 'ExampleOracleSimple: INVALID_TOKEN');
            amountOut = price1Average.mul(amountIn).decode144();
        }
    }
}


// File contracts/examples/ExampleSlidingWindowOracle.sol

pragma solidity =0.6.6;





// sliding window oracle that uses observations collected over a window to provide moving price averages in the past
// `windowSize` with a precision of `windowSize / granularity`
// note this is a singleton oracle and only needs to be deployed once per desired parameters, which
// differs from the simple oracle which must be deployed once per pair.
contract ExampleSlidingWindowOracle {
    using FixedPoint for *;
    using SafeMath for uint;

    struct Observation {
        uint timestamp;
        uint price0Cumulative;
        uint price1Cumulative;
    }

    address public immutable factory;
    // the desired amount of time over which the moving average should be computed, e.g. 24 hours
    uint public immutable windowSize;
    // the number of observations stored for each pair, i.e. how many price observations are stored for the window.
    // as granularity increases from 1, more frequent updates are needed, but moving averages become more precise.
    // averages are computed over intervals with sizes in the range:
    //   [windowSize - (windowSize / granularity) * 2, windowSize]
    // e.g. if the window size is 24 hours, and the granularity is 24, the oracle will return the average price for
    //   the period:
    //   [now - [22 hours, 24 hours], now]
    uint8 public immutable granularity;
    // this is redundant with granularity and windowSize, but stored for gas savings & informational purposes.
    uint public immutable periodSize;

    // mapping from pair address to a list of price observations of that pair
    mapping(address => Observation[]) public pairObservations;

    constructor(address factory_, uint windowSize_, uint8 granularity_) public {
        require(granularity_ > 1, 'SlidingWindowOracle: GRANULARITY');
        require(
            (periodSize = windowSize_ / granularity_) * granularity_ == windowSize_,
            'SlidingWindowOracle: WINDOW_NOT_EVENLY_DIVISIBLE'
        );
        factory = factory_;
        windowSize = windowSize_;
        granularity = granularity_;
    }

    // returns the index of the observation corresponding to the given timestamp
    function observationIndexOf(uint timestamp) public view returns (uint8 index) {
        uint epochPeriod = timestamp / periodSize;
        return uint8(epochPeriod % granularity);
    }

    // returns the observation from the oldest epoch (at the beginning of the window) relative to the current time
    function getFirstObservationInWindow(address pair) private view returns (Observation storage firstObservation) {
        uint8 observationIndex = observationIndexOf(block.timestamp);
        // no overflow issue. if observationIndex + 1 overflows, result is still zero.
        uint8 firstObservationIndex = (observationIndex + 1) % granularity;
        firstObservation = pairObservations[pair][firstObservationIndex];
    }

    // update the cumulative price for the observation at the current timestamp. each observation is updated at most
    // once per epoch period.
    function update(address tokenA, address tokenB) external {
        address pair = PancakeLibrary.pairFor(factory, tokenA, tokenB);

        // populate the array with empty observations (first call only)
        for (uint i = pairObservations[pair].length; i < granularity; i++) {
            pairObservations[pair].push();
        }

        // get the observation for the current period
        uint8 observationIndex = observationIndexOf(block.timestamp);
        Observation storage observation = pairObservations[pair][observationIndex];

        // we only want to commit updates once per period (i.e. windowSize / granularity)
        uint timeElapsed = block.timestamp - observation.timestamp;
        if (timeElapsed > periodSize) {
            (uint price0Cumulative, uint price1Cumulative,) = PancakeOracleLibrary.currentCumulativePrices(pair);
            observation.timestamp = block.timestamp;
            observation.price0Cumulative = price0Cumulative;
            observation.price1Cumulative = price1Cumulative;
        }
    }

    // given the cumulative prices of the start and end of a period, and the length of the period, compute the average
    // price in terms of how much amount out is received for the amount in
    function computeAmountOut(
        uint priceCumulativeStart, uint priceCumulativeEnd,
        uint timeElapsed, uint amountIn
    ) private pure returns (uint amountOut) {
        // overflow is desired.
        FixedPoint.uq112x112 memory priceAverage = FixedPoint.uq112x112(
            uint224((priceCumulativeEnd - priceCumulativeStart) / timeElapsed)
        );
        amountOut = priceAverage.mul(amountIn).decode144();
    }

    // returns the amount out corresponding to the amount in for a given token using the moving average over the time
    // range [now - [windowSize, windowSize - periodSize * 2], now]
    // update must have been called for the bucket corresponding to timestamp `now - windowSize`
    function consult(address tokenIn, uint amountIn, address tokenOut) external view returns (uint amountOut) {
        address pair = PancakeLibrary.pairFor(factory, tokenIn, tokenOut);
        Observation storage firstObservation = getFirstObservationInWindow(pair);

        uint timeElapsed = block.timestamp - firstObservation.timestamp;
        require(timeElapsed <= windowSize, 'SlidingWindowOracle: MISSING_HISTORICAL_OBSERVATION');
        // should never happen.
        require(timeElapsed >= windowSize - periodSize * 2, 'SlidingWindowOracle: UNEXPECTED_TIME_ELAPSED');

        (uint price0Cumulative, uint price1Cumulative,) = PancakeOracleLibrary.currentCumulativePrices(pair);
        (address token0,) = PancakeLibrary.sortTokens(tokenIn, tokenOut);

        if (token0 == tokenIn) {
            return computeAmountOut(firstObservation.price0Cumulative, price0Cumulative, timeElapsed, amountIn);
        } else {
            return computeAmountOut(firstObservation.price1Cumulative, price1Cumulative, timeElapsed, amountIn);
        }
    }
}


// File @uniswap/lib/contracts/libraries/Babylonian.sol@v1.1.1

pragma solidity >=0.4.0;

// computes square roots using the babylonian method
// https://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Babylonian_method
library Babylonian {
    function sqrt(uint y) internal pure returns (uint z) {
        if (y > 3) {
            z = y;
            uint x = y / 2 + 1;
            while (x < z) {
                z = x;
                x = (y / x + x) / 2;
            }
        } else if (y != 0) {
            z = 1;
        }
        // else z = 0
    }
}


// File @uniswap/lib/contracts/libraries/TransferHelper.sol@v1.1.1

pragma solidity >=0.6.0;

// helper methods for interacting with ERC20 tokens and sending ETH that do not consistently return true/false
library TransferHelper {
    function safeApprove(address token, address to, uint value) internal {
        // bytes4(keccak256(bytes('approve(address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x095ea7b3, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: APPROVE_FAILED');
    }

    function safeTransfer(address token, address to, uint value) internal {
        // bytes4(keccak256(bytes('transfer(address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0xa9059cbb, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FAILED');
    }

    function safeTransferFrom(address token, address from, address to, uint value) internal {
        // bytes4(keccak256(bytes('transferFrom(address,address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x23b872dd, from, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FROM_FAILED');
    }

    function safeTransferETH(address to, uint value) internal {
        (bool success,) = to.call{value:value}(new bytes(0));
        require(success, 'TransferHelper: ETH_TRANSFER_FAILED');
    }
}


// File contracts/examples/ExampleSwapToPrice.sol

pragma solidity =0.6.6;






contract ExampleSwapToPrice {
    using SafeMath for uint256;

    IPancakeRouter01 public immutable router;
    address public immutable factory;

    constructor(address factory_, IPancakeRouter01 router_) public {
        factory = factory_;
        router = router_;
    }

    // computes the direction and magnitude of the profit-maximizing trade
    function computeProfitMaximizingTrade(
        uint256 truePriceTokenA,
        uint256 truePriceTokenB,
        uint256 reserveA,
        uint256 reserveB
    ) pure public returns (bool aToB, uint256 amountIn) {
        aToB = reserveA.mul(truePriceTokenB) / reserveB < truePriceTokenA;

        uint256 invariant = reserveA.mul(reserveB);

        uint256 leftSide = Babylonian.sqrt(
            invariant.mul(aToB ? truePriceTokenA : truePriceTokenB).mul(1000) /
            uint256(aToB ? truePriceTokenB : truePriceTokenA).mul(997)
        );
        uint256 rightSide = (aToB ? reserveA.mul(1000) : reserveB.mul(1000)) / 997;

        // compute the amount that must be sent to move the price to the profit-maximizing price
        amountIn = leftSide.sub(rightSide);
    }

    // swaps an amount of either token such that the trade is profit-maximizing, given an external true price
    // true price is expressed in the ratio of token A to token B
    // caller must approve this contract to spend whichever token is intended to be swapped
    function swapToPrice(
        address tokenA,
        address tokenB,
        uint256 truePriceTokenA,
        uint256 truePriceTokenB,
        uint256 maxSpendTokenA,
        uint256 maxSpendTokenB,
        address to,
        uint256 deadline
    ) public {
        // true price is expressed as a ratio, so both values must be non-zero
        require(truePriceTokenA != 0 && truePriceTokenB != 0, "ExampleSwapToPrice: ZERO_PRICE");
        // caller can specify 0 for either if they wish to swap in only one direction, but not both
        require(maxSpendTokenA != 0 || maxSpendTokenB != 0, "ExampleSwapToPrice: ZERO_SPEND");

        bool aToB;
        uint256 amountIn;
        {
            (uint256 reserveA, uint256 reserveB) = PancakeLibrary.getReserves(factory, tokenA, tokenB);
            (aToB, amountIn) = computeProfitMaximizingTrade(
                truePriceTokenA, truePriceTokenB,
                reserveA, reserveB
            );
        }

        // spend up to the allowance of the token in
        uint256 maxSpend = aToB ? maxSpendTokenA : maxSpendTokenB;
        if (amountIn > maxSpend) {
            amountIn = maxSpend;
        }

        address tokenIn = aToB ? tokenA : tokenB;
        address tokenOut = aToB ? tokenB : tokenA;
        TransferHelper.safeTransferFrom(tokenIn, msg.sender, address(this), amountIn);
        TransferHelper.safeApprove(tokenIn, address(router), amountIn);

        address[] memory path = new address[](2);
        path[0] = tokenIn;
        path[1] = tokenOut;

        router.swapExactTokensForTokens(
            amountIn,
            0, // amountOutMin: we can skip computing this number because the math is tested
            path,
            to,
            deadline
        );
    }
}


// File contracts/interfaces/IPancakeRouter02.sol

pragma solidity >=0.6.2;

interface IPancakeRouter02 is IPancakeRouter01 {
    function removeLiquidityETHSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountETH);
    function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountETH);

    function swapExactTokensForTokensSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
    function swapExactETHForTokensSupportingFeeOnTransferTokens(
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external payable;
    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
}


// File contracts/interfaces/IPancakeMigrator.sol

pragma solidity >=0.5.0;

interface IPancakeMigrator {
    function migrate(address token, uint amountTokenMin, uint amountETHMin, address to, uint deadline) external;
}


// File contracts/PancakeMigrator.sol

pragma solidity =0.6.6;





contract PancakeMigrator is IPancakeMigrator {
    IUniswapV1Factory immutable factoryV1;
    IPancakeRouter01 immutable router;

    constructor(address _factoryV1, address _router) public {
        factoryV1 = IUniswapV1Factory(_factoryV1);
        router = IPancakeRouter01(_router);
    }

    // needs to accept ETH from any v1 exchange and the router. ideally this could be enforced, as in the router,
    // but it's not possible because it requires a call to the v1 factory, which takes too much gas
    receive() external payable {}

    function migrate(address token, uint amountTokenMin, uint amountETHMin, address to, uint deadline)
        external
        override
    {
        IUniswapV1Exchange exchangeV1 = IUniswapV1Exchange(factoryV1.getExchange(token));
        uint liquidityV1 = exchangeV1.balanceOf(msg.sender);
        require(exchangeV1.transferFrom(msg.sender, address(this), liquidityV1), 'TRANSFER_FROM_FAILED');
        (uint amountETHV1, uint amountTokenV1) = exchangeV1.removeLiquidity(liquidityV1, 1, 1, uint(-1));
        TransferHelper.safeApprove(token, address(router), amountTokenV1);
        (uint amountTokenV2, uint amountETHV2,) = router.addLiquidityETH{value: amountETHV1}(
            token,
            amountTokenV1,
            amountTokenMin,
            amountETHMin,
            to,
            deadline
        );
        if (amountTokenV1 > amountTokenV2) {
            TransferHelper.safeApprove(token, address(router), 0); // be a good blockchain citizen, reset allowance to 0
            TransferHelper.safeTransfer(token, msg.sender, amountTokenV1 - amountTokenV2);
        } else if (amountETHV1 > amountETHV2) {
            // addLiquidityETH guarantees that all of amountETHV1 or amountTokenV1 will be used, hence this else is safe
            TransferHelper.safeTransferETH(msg.sender, amountETHV1 - amountETHV2);
        }
    }
}


// File contracts/PancakeRouter.sol

pragma solidity =0.6.6;






contract PancakeRouter is IPancakeRouter02 {
    using SafeMath for uint;

    address public immutable override factory;
    address public immutable override WETH;

    modifier ensure(uint deadline) {
        require(deadline >= block.timestamp, 'PancakeRouter: EXPIRED');
        _;
    }

    constructor(address _factory, address _WETH) public {
        factory = _factory;
        WETH = _WETH;
    }

    receive() external payable {
        assert(msg.sender == WETH); // only accept ETH via fallback from the WETH contract
    }

    // **** ADD LIQUIDITY ****
    function _addLiquidity(
        address tokenA,
        address tokenB,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin
    ) internal virtual returns (uint amountA, uint amountB) {
        // create the pair if it doesn't exist yet
        if (IUniswapV2Factory(factory).getPair(tokenA, tokenB) == address(0)) {
            IUniswapV2Factory(factory).createPair(tokenA, tokenB);
        }
        (uint reserveA, uint reserveB) = PancakeLibrary.getReserves(factory, tokenA, tokenB);
        if (reserveA == 0 && reserveB == 0) {
            (amountA, amountB) = (amountADesired, amountBDesired);
        } else {
            uint amountBOptimal = PancakeLibrary.quote(amountADesired, reserveA, reserveB);
            if (amountBOptimal <= amountBDesired) {
                require(amountBOptimal >= amountBMin, 'PancakeRouter: INSUFFICIENT_B_AMOUNT');
                (amountA, amountB) = (amountADesired, amountBOptimal);
            } else {
                uint amountAOptimal = PancakeLibrary.quote(amountBDesired, reserveB, reserveA);
                assert(amountAOptimal <= amountADesired);
                require(amountAOptimal >= amountAMin, 'PancakeRouter: INSUFFICIENT_A_AMOUNT');
                (amountA, amountB) = (amountAOptimal, amountBDesired);
            }
        }
    }
    function addLiquidity(
        address tokenA,
        address tokenB,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external virtual override ensure(deadline) returns (uint amountA, uint amountB, uint liquidity) {
        (amountA, amountB) = _addLiquidity(tokenA, tokenB, amountADesired, amountBDesired, amountAMin, amountBMin);
        address pair = PancakeLibrary.pairFor(factory, tokenA, tokenB);
        TransferHelper.safeTransferFrom(tokenA, msg.sender, pair, amountA);
        TransferHelper.safeTransferFrom(tokenB, msg.sender, pair, amountB);
        liquidity = IUniswapV2Pair(pair).mint(to);
    }
    function addLiquidityETH(
        address token,
        uint amountTokenDesired,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external virtual override payable ensure(deadline) returns (uint amountToken, uint amountETH, uint liquidity) {
        (amountToken, amountETH) = _addLiquidity(
            token,
            WETH,
            amountTokenDesired,
            msg.value,
            amountTokenMin,
            amountETHMin
        );
        address pair = PancakeLibrary.pairFor(factory, token, WETH);
        TransferHelper.safeTransferFrom(token, msg.sender, pair, amountToken);
        IWETH(WETH).deposit{value: amountETH}();
        assert(IWETH(WETH).transfer(pair, amountETH));
        liquidity = IUniswapV2Pair(pair).mint(to);
        // refund dust eth, if any
        if (msg.value > amountETH) TransferHelper.safeTransferETH(msg.sender, msg.value - amountETH);
    }

    // **** REMOVE LIQUIDITY ****
    function removeLiquidity(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) public virtual override ensure(deadline) returns (uint amountA, uint amountB) {
        address pair = PancakeLibrary.pairFor(factory, tokenA, tokenB);
        IUniswapV2Pair(pair).transferFrom(msg.sender, pair, liquidity); // send liquidity to pair
        (uint amount0, uint amount1) = IUniswapV2Pair(pair).burn(to);
        (address token0,) = PancakeLibrary.sortTokens(tokenA, tokenB);
        (amountA, amountB) = tokenA == token0 ? (amount0, amount1) : (amount1, amount0);
        require(amountA >= amountAMin, 'PancakeRouter: INSUFFICIENT_A_AMOUNT');
        require(amountB >= amountBMin, 'PancakeRouter: INSUFFICIENT_B_AMOUNT');
    }
    function removeLiquidityETH(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) public virtual override ensure(deadline) returns (uint amountToken, uint amountETH) {
        (amountToken, amountETH) = removeLiquidity(
            token,
            WETH,
            liquidity,
            amountTokenMin,
            amountETHMin,
            address(this),
            deadline
        );
        TransferHelper.safeTransfer(token, to, amountToken);
        IWETH(WETH).withdraw(amountETH);
        TransferHelper.safeTransferETH(to, amountETH);
    }
    function removeLiquidityWithPermit(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external virtual override returns (uint amountA, uint amountB) {
        address pair = PancakeLibrary.pairFor(factory, tokenA, tokenB);
        uint value = approveMax ? uint(-1) : liquidity;
        IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);
        (amountA, amountB) = removeLiquidity(tokenA, tokenB, liquidity, amountAMin, amountBMin, to, deadline);
    }
    function removeLiquidityETHWithPermit(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external virtual override returns (uint amountToken, uint amountETH) {
        address pair = PancakeLibrary.pairFor(factory, token, WETH);
        uint value = approveMax ? uint(-1) : liquidity;
        IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);
        (amountToken, amountETH) = removeLiquidityETH(token, liquidity, amountTokenMin, amountETHMin, to, deadline);
    }

    // **** REMOVE LIQUIDITY (supporting fee-on-transfer tokens) ****
    function removeLiquidityETHSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) public virtual override ensure(deadline) returns (uint amountETH) {
        (, amountETH) = removeLiquidity(
            token,
            WETH,
            liquidity,
            amountTokenMin,
            amountETHMin,
            address(this),
            deadline
        );
        TransferHelper.safeTransfer(token, to, IERC20(token).balanceOf(address(this)));
        IWETH(WETH).withdraw(amountETH);
        TransferHelper.safeTransferETH(to, amountETH);
    }
    function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external virtual override returns (uint amountETH) {
        address pair = PancakeLibrary.pairFor(factory, token, WETH);
        uint value = approveMax ? uint(-1) : liquidity;
        IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);
        amountETH = removeLiquidityETHSupportingFeeOnTransferTokens(
            token, liquidity, amountTokenMin, amountETHMin, to, deadline
        );
    }

    // **** SWAP ****
    // requires the initial amount to have already been sent to the first pair
    function _swap(uint[] memory amounts, address[] memory path, address _to) internal virtual {
        for (uint i; i < path.length - 1; i++) {
            (address input, address output) = (path[i], path[i + 1]);
            (address token0,) = PancakeLibrary.sortTokens(input, output);
            uint amountOut = amounts[i + 1];
            (uint amount0Out, uint amount1Out) = input == token0 ? (uint(0), amountOut) : (amountOut, uint(0));
            address to = i < path.length - 2 ? PancakeLibrary.pairFor(factory, output, path[i + 2]) : _to;
            IUniswapV2Pair(PancakeLibrary.pairFor(factory, input, output)).swap(
                amount0Out, amount1Out, to, new bytes(0)
            );
        }
    }
    function swapExactTokensForTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external virtual override ensure(deadline) returns (uint[] memory amounts) {
        amounts = PancakeLibrary.getAmountsOut(factory, amountIn, path);
        require(amounts[amounts.length - 1] >= amountOutMin, 'PancakeRouter: INSUFFICIENT_OUTPUT_AMOUNT');
        TransferHelper.safeTransferFrom(
            path[0], msg.sender, PancakeLibrary.pairFor(factory, path[0], path[1]), amounts[0]
        );
        _swap(amounts, path, to);
    }
    function swapTokensForExactTokens(
        uint amountOut,
        uint amountInMax,
        address[] calldata path,
        address to,
        uint deadline
    ) external virtual override ensure(deadline) returns (uint[] memory amounts) {
        amounts = PancakeLibrary.getAmountsIn(factory, amountOut, path);
        require(amounts[0] <= amountInMax, 'PancakeRouter: EXCESSIVE_INPUT_AMOUNT');
        TransferHelper.safeTransferFrom(
            path[0], msg.sender, PancakeLibrary.pairFor(factory, path[0], path[1]), amounts[0]
        );
        _swap(amounts, path, to);
    }
    function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        virtual
        override
        payable
        ensure(deadline)
        returns (uint[] memory amounts)
    {
        require(path[0] == WETH, 'PancakeRouter: INVALID_PATH');
        amounts = PancakeLibrary.getAmountsOut(factory, msg.value, path);
        require(amounts[amounts.length - 1] >= amountOutMin, 'PancakeRouter: INSUFFICIENT_OUTPUT_AMOUNT');
        IWETH(WETH).deposit{value: amounts[0]}();
        assert(IWETH(WETH).transfer(PancakeLibrary.pairFor(factory, path[0], path[1]), amounts[0]));
        _swap(amounts, path, to);
    }
    function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
        external
        virtual
        override
        ensure(deadline)
        returns (uint[] memory amounts)
    {
        require(path[path.length - 1] == WETH, 'PancakeRouter: INVALID_PATH');
        amounts = PancakeLibrary.getAmountsIn(factory, amountOut, path);
        require(amounts[0] <= amountInMax, 'PancakeRouter: EXCESSIVE_INPUT_AMOUNT');
        TransferHelper.safeTransferFrom(
            path[0], msg.sender, PancakeLibrary.pairFor(factory, path[0], path[1]), amounts[0]
        );
        _swap(amounts, path, address(this));
        IWETH(WETH).withdraw(amounts[amounts.length - 1]);
        TransferHelper.safeTransferETH(to, amounts[amounts.length - 1]);
    }
    function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        virtual
        override
        ensure(deadline)
        returns (uint[] memory amounts)
    {
        require(path[path.length - 1] == WETH, 'PancakeRouter: INVALID_PATH');
        amounts = PancakeLibrary.getAmountsOut(factory, amountIn, path);
        require(amounts[amounts.length - 1] >= amountOutMin, 'PancakeRouter: INSUFFICIENT_OUTPUT_AMOUNT');
        TransferHelper.safeTransferFrom(
            path[0], msg.sender, PancakeLibrary.pairFor(factory, path[0], path[1]), amounts[0]
        );
        _swap(amounts, path, address(this));
        IWETH(WETH).withdraw(amounts[amounts.length - 1]);
        TransferHelper.safeTransferETH(to, amounts[amounts.length - 1]);
    }
    function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
        external
        virtual
        override
        payable
        ensure(deadline)
        returns (uint[] memory amounts)
    {
        require(path[0] == WETH, 'PancakeRouter: INVALID_PATH');
        amounts = PancakeLibrary.getAmountsIn(factory, amountOut, path);
        require(amounts[0] <= msg.value, 'PancakeRouter: EXCESSIVE_INPUT_AMOUNT');
        IWETH(WETH).deposit{value: amounts[0]}();
        assert(IWETH(WETH).transfer(PancakeLibrary.pairFor(factory, path[0], path[1]), amounts[0]));
        _swap(amounts, path, to);
        // refund dust eth, if any
        if (msg.value > amounts[0]) TransferHelper.safeTransferETH(msg.sender, msg.value - amounts[0]);
    }

    // **** SWAP (supporting fee-on-transfer tokens) ****
    // requires the initial amount to have already been sent to the first pair
    function _swapSupportingFeeOnTransferTokens(address[] memory path, address _to) internal virtual {
        for (uint i; i < path.length - 1; i++) {
            (address input, address output) = (path[i], path[i + 1]);
            (address token0,) = PancakeLibrary.sortTokens(input, output);
            IUniswapV2Pair pair = IUniswapV2Pair(PancakeLibrary.pairFor(factory, input, output));
            uint amountInput;
            uint amountOutput;
            { // scope to avoid stack too deep errors
            (uint reserve0, uint reserve1,) = pair.getReserves();
            (uint reserveInput, uint reserveOutput) = input == token0 ? (reserve0, reserve1) : (reserve1, reserve0);
            amountInput = IERC20(input).balanceOf(address(pair)).sub(reserveInput);
            amountOutput = PancakeLibrary.getAmountOut(amountInput, reserveInput, reserveOutput);
            }
            (uint amount0Out, uint amount1Out) = input == token0 ? (uint(0), amountOutput) : (amountOutput, uint(0));
            address to = i < path.length - 2 ? PancakeLibrary.pairFor(factory, output, path[i + 2]) : _to;
            pair.swap(amount0Out, amount1Out, to, new bytes(0));
        }
    }
    function swapExactTokensForTokensSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external virtual override ensure(deadline) {
        TransferHelper.safeTransferFrom(
            path[0], msg.sender, PancakeLibrary.pairFor(factory, path[0], path[1]), amountIn
        );
        uint balanceBefore = IERC20(path[path.length - 1]).balanceOf(to);
        _swapSupportingFeeOnTransferTokens(path, to);
        require(
            IERC20(path[path.length - 1]).balanceOf(to).sub(balanceBefore) >= amountOutMin,
            'PancakeRouter: INSUFFICIENT_OUTPUT_AMOUNT'
        );
    }
    function swapExactETHForTokensSupportingFeeOnTransferTokens(
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    )
        external
        virtual
        override
        payable
        ensure(deadline)
    {
        require(path[0] == WETH, 'PancakeRouter: INVALID_PATH');
        uint amountIn = msg.value;
        IWETH(WETH).deposit{value: amountIn}();
        assert(IWETH(WETH).transfer(PancakeLibrary.pairFor(factory, path[0], path[1]), amountIn));
        uint balanceBefore = IERC20(path[path.length - 1]).balanceOf(to);
        _swapSupportingFeeOnTransferTokens(path, to);
        require(
            IERC20(path[path.length - 1]).balanceOf(to).sub(balanceBefore) >= amountOutMin,
            'PancakeRouter: INSUFFICIENT_OUTPUT_AMOUNT'
        );
    }
    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    )
        external
        virtual
        override
        ensure(deadline)
    {
        require(path[path.length - 1] == WETH, 'PancakeRouter: INVALID_PATH');
        TransferHelper.safeTransferFrom(
            path[0], msg.sender, PancakeLibrary.pairFor(factory, path[0], path[1]), amountIn
        );
        _swapSupportingFeeOnTransferTokens(path, address(this));
        uint amountOut = IERC20(WETH).balanceOf(address(this));
        require(amountOut >= amountOutMin, 'PancakeRouter: INSUFFICIENT_OUTPUT_AMOUNT');
        IWETH(WETH).withdraw(amountOut);
        TransferHelper.safeTransferETH(to, amountOut);
    }

    // **** LIBRARY FUNCTIONS ****
    function quote(uint amountA, uint reserveA, uint reserveB) public pure virtual override returns (uint amountB) {
        return PancakeLibrary.quote(amountA, reserveA, reserveB);
    }

    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut)
        public
        pure
        virtual
        override
        returns (uint amountOut)
    {
        return PancakeLibrary.getAmountOut(amountIn, reserveIn, reserveOut);
    }

    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut)
        public
        pure
        virtual
        override
        returns (uint amountIn)
    {
        return PancakeLibrary.getAmountIn(amountOut, reserveIn, reserveOut);
    }

    function getAmountsOut(uint amountIn, address[] memory path)
        public
        view
        virtual
        override
        returns (uint[] memory amounts)
    {
        return PancakeLibrary.getAmountsOut(factory, amountIn, path);
    }

    function getAmountsIn(uint amountOut, address[] memory path)
        public
        view
        virtual
        override
        returns (uint[] memory amounts)
    {
        return PancakeLibrary.getAmountsIn(factory, amountOut, path);
    }
}


// File contracts/PancakeRouter01.sol

pragma solidity =0.6.6;





contract PancakeRouter01 is IPancakeRouter01 {
    address public immutable override factory;
    address public immutable override WETH;

    modifier ensure(uint deadline) {
        require(deadline >= block.timestamp, 'PancakeRouter: EXPIRED');
        _;
    }

    constructor(address _factory, address _WETH) public {
        factory = _factory;
        WETH = _WETH;
    }

    receive() external payable {
        assert(msg.sender == WETH); // only accept ETH via fallback from the WETH contract
    }

    // **** ADD LIQUIDITY ****
    function _addLiquidity(
        address tokenA,
        address tokenB,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin
    ) private returns (uint amountA, uint amountB) {
        // create the pair if it doesn't exist yet
        if (IUniswapV2Factory(factory).getPair(tokenA, tokenB) == address(0)) {
            IUniswapV2Factory(factory).createPair(tokenA, tokenB);
        }
        (uint reserveA, uint reserveB) = PancakeLibrary.getReserves(factory, tokenA, tokenB);
        if (reserveA == 0 && reserveB == 0) {
            (amountA, amountB) = (amountADesired, amountBDesired);
        } else {
            uint amountBOptimal = PancakeLibrary.quote(amountADesired, reserveA, reserveB);
            if (amountBOptimal <= amountBDesired) {
                require(amountBOptimal >= amountBMin, 'PancakeRouter: INSUFFICIENT_B_AMOUNT');
                (amountA, amountB) = (amountADesired, amountBOptimal);
            } else {
                uint amountAOptimal = PancakeLibrary.quote(amountBDesired, reserveB, reserveA);
                assert(amountAOptimal <= amountADesired);
                require(amountAOptimal >= amountAMin, 'PancakeRouter: INSUFFICIENT_A_AMOUNT');
                (amountA, amountB) = (amountAOptimal, amountBDesired);
            }
        }
    }
    function addLiquidity(
        address tokenA,
        address tokenB,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external override ensure(deadline) returns (uint amountA, uint amountB, uint liquidity) {
        (amountA, amountB) = _addLiquidity(tokenA, tokenB, amountADesired, amountBDesired, amountAMin, amountBMin);
        address pair = PancakeLibrary.pairFor(factory, tokenA, tokenB);
        TransferHelper.safeTransferFrom(tokenA, msg.sender, pair, amountA);
        TransferHelper.safeTransferFrom(tokenB, msg.sender, pair, amountB);
        liquidity = IUniswapV2Pair(pair).mint(to);
    }
    function addLiquidityETH(
        address token,
        uint amountTokenDesired,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external override payable ensure(deadline) returns (uint amountToken, uint amountETH, uint liquidity) {
        (amountToken, amountETH) = _addLiquidity(
            token,
            WETH,
            amountTokenDesired,
            msg.value,
            amountTokenMin,
            amountETHMin
        );
        address pair = PancakeLibrary.pairFor(factory, token, WETH);
        TransferHelper.safeTransferFrom(token, msg.sender, pair, amountToken);
        IWETH(WETH).deposit{value: amountETH}();
        assert(IWETH(WETH).transfer(pair, amountETH));
        liquidity = IUniswapV2Pair(pair).mint(to);
        if (msg.value > amountETH) TransferHelper.safeTransferETH(msg.sender, msg.value - amountETH); // refund dust eth, if any
    }

    // **** REMOVE LIQUIDITY ****
    function removeLiquidity(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) public override ensure(deadline) returns (uint amountA, uint amountB) {
        address pair = PancakeLibrary.pairFor(factory, tokenA, tokenB);
        IUniswapV2Pair(pair).transferFrom(msg.sender, pair, liquidity); // send liquidity to pair
        (uint amount0, uint amount1) = IUniswapV2Pair(pair).burn(to);
        (address token0,) = PancakeLibrary.sortTokens(tokenA, tokenB);
        (amountA, amountB) = tokenA == token0 ? (amount0, amount1) : (amount1, amount0);
        require(amountA >= amountAMin, 'PancakeRouter: INSUFFICIENT_A_AMOUNT');
        require(amountB >= amountBMin, 'PancakeRouter: INSUFFICIENT_B_AMOUNT');
    }
    function removeLiquidityETH(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) public override ensure(deadline) returns (uint amountToken, uint amountETH) {
        (amountToken, amountETH) = removeLiquidity(
            token,
            WETH,
            liquidity,
            amountTokenMin,
            amountETHMin,
            address(this),
            deadline
        );
        TransferHelper.safeTransfer(token, to, amountToken);
        IWETH(WETH).withdraw(amountETH);
        TransferHelper.safeTransferETH(to, amountETH);
    }
    function removeLiquidityWithPermit(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external override returns (uint amountA, uint amountB) {
        address pair = PancakeLibrary.pairFor(factory, tokenA, tokenB);
        uint value = approveMax ? uint(-1) : liquidity;
        IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);
        (amountA, amountB) = removeLiquidity(tokenA, tokenB, liquidity, amountAMin, amountBMin, to, deadline);
    }
    function removeLiquidityETHWithPermit(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external override returns (uint amountToken, uint amountETH) {
        address pair = PancakeLibrary.pairFor(factory, token, WETH);
        uint value = approveMax ? uint(-1) : liquidity;
        IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);
        (amountToken, amountETH) = removeLiquidityETH(token, liquidity, amountTokenMin, amountETHMin, to, deadline);
    }

    // **** SWAP ****
    // requires the initial amount to have already been sent to the first pair
    function _swap(uint[] memory amounts, address[] memory path, address _to) private {
        for (uint i; i < path.length - 1; i++) {
            (address input, address output) = (path[i], path[i + 1]);
            (address token0,) = PancakeLibrary.sortTokens(input, output);
            uint amountOut = amounts[i + 1];
            (uint amount0Out, uint amount1Out) = input == token0 ? (uint(0), amountOut) : (amountOut, uint(0));
            address to = i < path.length - 2 ? PancakeLibrary.pairFor(factory, output, path[i + 2]) : _to;
            IUniswapV2Pair(PancakeLibrary.pairFor(factory, input, output)).swap(amount0Out, amount1Out, to, new bytes(0));
        }
    }
    function swapExactTokensForTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external override ensure(deadline) returns (uint[] memory amounts) {
        amounts = PancakeLibrary.getAmountsOut(factory, amountIn, path);
        require(amounts[amounts.length - 1] >= amountOutMin, 'PancakeRouter: INSUFFICIENT_OUTPUT_AMOUNT');
        TransferHelper.safeTransferFrom(path[0], msg.sender, PancakeLibrary.pairFor(factory, path[0], path[1]), amounts[0]);
        _swap(amounts, path, to);
    }
    function swapTokensForExactTokens(
        uint amountOut,
        uint amountInMax,
        address[] calldata path,
        address to,
        uint deadline
    ) external override ensure(deadline) returns (uint[] memory amounts) {
        amounts = PancakeLibrary.getAmountsIn(factory, amountOut, path);
        require(amounts[0] <= amountInMax, 'PancakeRouter: EXCESSIVE_INPUT_AMOUNT');
        TransferHelper.safeTransferFrom(path[0], msg.sender, PancakeLibrary.pairFor(factory, path[0], path[1]), amounts[0]);
        _swap(amounts, path, to);
    }
    function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        override
        payable
        ensure(deadline)
        returns (uint[] memory amounts)
    {
        require(path[0] == WETH, 'PancakeRouter: INVALID_PATH');
        amounts = PancakeLibrary.getAmountsOut(factory, msg.value, path);
        require(amounts[amounts.length - 1] >= amountOutMin, 'PancakeRouter: INSUFFICIENT_OUTPUT_AMOUNT');
        IWETH(WETH).deposit{value: amounts[0]}();
        assert(IWETH(WETH).transfer(PancakeLibrary.pairFor(factory, path[0], path[1]), amounts[0]));
        _swap(amounts, path, to);
    }
    function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
        external
        override
        ensure(deadline)
        returns (uint[] memory amounts)
    {
        require(path[path.length - 1] == WETH, 'PancakeRouter: INVALID_PATH');
        amounts = PancakeLibrary.getAmountsIn(factory, amountOut, path);
        require(amounts[0] <= amountInMax, 'PancakeRouter: EXCESSIVE_INPUT_AMOUNT');
        TransferHelper.safeTransferFrom(path[0], msg.sender, PancakeLibrary.pairFor(factory, path[0], path[1]), amounts[0]);
        _swap(amounts, path, address(this));
        IWETH(WETH).withdraw(amounts[amounts.length - 1]);
        TransferHelper.safeTransferETH(to, amounts[amounts.length - 1]);
    }
    function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        override
        ensure(deadline)
        returns (uint[] memory amounts)
    {
        require(path[path.length - 1] == WETH, 'PancakeRouter: INVALID_PATH');
        amounts = PancakeLibrary.getAmountsOut(factory, amountIn, path);
        require(amounts[amounts.length - 1] >= amountOutMin, 'PancakeRouter: INSUFFICIENT_OUTPUT_AMOUNT');
        TransferHelper.safeTransferFrom(path[0], msg.sender, PancakeLibrary.pairFor(factory, path[0], path[1]), amounts[0]);
        _swap(amounts, path, address(this));
        IWETH(WETH).withdraw(amounts[amounts.length - 1]);
        TransferHelper.safeTransferETH(to, amounts[amounts.length - 1]);
    }
    function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
        external
        override
        payable
        ensure(deadline)
        returns (uint[] memory amounts)
    {
        require(path[0] == WETH, 'PancakeRouter: INVALID_PATH');
        amounts = PancakeLibrary.getAmountsIn(factory, amountOut, path);
        require(amounts[0] <= msg.value, 'PancakeRouter: EXCESSIVE_INPUT_AMOUNT');
        IWETH(WETH).deposit{value: amounts[0]}();
        assert(IWETH(WETH).transfer(PancakeLibrary.pairFor(factory, path[0], path[1]), amounts[0]));
        _swap(amounts, path, to);
        if (msg.value > amounts[0]) TransferHelper.safeTransferETH(msg.sender, msg.value - amounts[0]); // refund dust eth, if any
    }

    function quote(uint amountA, uint reserveA, uint reserveB) public pure override returns (uint amountB) {
        return PancakeLibrary.quote(amountA, reserveA, reserveB);
    }

    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) public pure override returns (uint amountOut) {
        return PancakeLibrary.getAmountOut(amountIn, reserveIn, reserveOut);
    }

    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) public pure override returns (uint amountIn) {
        return PancakeLibrary.getAmountOut(amountOut, reserveIn, reserveOut);
    }

    function getAmountsOut(uint amountIn, address[] memory path) public view override returns (uint[] memory amounts) {
        return PancakeLibrary.getAmountsOut(factory, amountIn, path);
    }

    function getAmountsIn(uint amountOut, address[] memory path) public view override returns (uint[] memory amounts) {
        return PancakeLibrary.getAmountsIn(factory, amountOut, path);
    }
}


// File contracts/test/DeflatingERC20.sol

pragma solidity =0.6.6;

contract DeflatingERC20 {
    using SafeMath for uint;

    string public constant name = 'Deflating Test Token';
    string public constant symbol = 'DTT';
    uint8 public constant decimals = 18;
    uint  public totalSupply;
    mapping(address => uint) public balanceOf;
    mapping(address => mapping(address => uint)) public allowance;

    bytes32 public DOMAIN_SEPARATOR;
    // keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
    bytes32 public constant PERMIT_TYPEHASH = 0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;
    mapping(address => uint) public nonces;

    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    constructor(uint _totalSupply) public {
        uint chainId;
        assembly {
            chainId := chainid()
        }
        DOMAIN_SEPARATOR = keccak256(
            abi.encode(
                keccak256('EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)'),
                keccak256(bytes(name)),
                keccak256(bytes('1')),
                chainId,
                address(this)
            )
        );
        _mint(msg.sender, _totalSupply);
    }

    function _mint(address to, uint value) internal {
        totalSupply = totalSupply.add(value);
        balanceOf[to] = balanceOf[to].add(value);
        emit Transfer(address(0), to, value);
    }

    function _burn(address from, uint value) internal {
        balanceOf[from] = balanceOf[from].sub(value);
        totalSupply = totalSupply.sub(value);
        emit Transfer(from, address(0), value);
    }

    function _approve(address owner, address spender, uint value) private {
        allowance[owner][spender] = value;
        emit Approval(owner, spender, value);
    }

    function _transfer(address from, address to, uint value) private {
        uint burnAmount = value / 100;
        _burn(from, burnAmount);
        uint transferAmount = value.sub(burnAmount);
        balanceOf[from] = balanceOf[from].sub(transferAmount);
        balanceOf[to] = balanceOf[to].add(transferAmount);
        emit Transfer(from, to, transferAmount);
    }

    function approve(address spender, uint value) external returns (bool) {
        _approve(msg.sender, spender, value);
        return true;
    }

    function transfer(address to, uint value) external returns (bool) {
        _transfer(msg.sender, to, value);
        return true;
    }

    function transferFrom(address from, address to, uint value) external returns (bool) {
        if (allowance[from][msg.sender] != uint(-1)) {
            allowance[from][msg.sender] = allowance[from][msg.sender].sub(value);
        }
        _transfer(from, to, value);
        return true;
    }

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external {
        require(deadline >= block.timestamp, 'EXPIRED');
        bytes32 digest = keccak256(
            abi.encodePacked(
                '\x19\x01',
                DOMAIN_SEPARATOR,
                keccak256(abi.encode(PERMIT_TYPEHASH, owner, spender, value, nonces[owner]++, deadline))
            )
        );
        address recoveredAddress = ecrecover(digest, v, r, s);
        require(recoveredAddress != address(0) && recoveredAddress == owner, 'INVALID_SIGNATURE');
        _approve(owner, spender, value);
    }
}


// File contracts/test/ERC20.sol

pragma solidity =0.6.6;

contract ERC20 {
    using SafeMath for uint;

    string public constant name = 'Test Token';
    string public constant symbol = 'TT';
    uint8 public constant decimals = 18;
    uint  public totalSupply;
    mapping(address => uint) public balanceOf;
    mapping(address => mapping(address => uint)) public allowance;

    bytes32 public DOMAIN_SEPARATOR;
    // keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
    bytes32 public constant PERMIT_TYPEHASH = 0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;
    mapping(address => uint) public nonces;

    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    constructor(uint _totalSupply) public {
        uint chainId;
        assembly {
            chainId := chainid()
        }
        DOMAIN_SEPARATOR = keccak256(
            abi.encode(
                keccak256('EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)'),
                keccak256(bytes(name)),
                keccak256(bytes('1')),
                chainId,
                address(this)
            )
        );
        _mint(msg.sender, _totalSupply);
    }

    function _mint(address to, uint value) internal {
        totalSupply = totalSupply.add(value);
        balanceOf[to] = balanceOf[to].add(value);
        emit Transfer(address(0), to, value);
    }

    function _burn(address from, uint value) internal {
        balanceOf[from] = balanceOf[from].sub(value);
        totalSupply = totalSupply.sub(value);
        emit Transfer(from, address(0), value);
    }

    function _approve(address owner, address spender, uint value) private {
        allowance[owner][spender] = value;
        emit Approval(owner, spender, value);
    }

    function _transfer(address from, address to, uint value) private {
        balanceOf[from] = balanceOf[from].sub(value);
        balanceOf[to] = balanceOf[to].add(value);
        emit Transfer(from, to, value);
    }

    function approve(address spender, uint value) external returns (bool) {
        _approve(msg.sender, spender, value);
        return true;
    }

    function transfer(address to, uint value) external returns (bool) {
        _transfer(msg.sender, to, value);
        return true;
    }

    function transferFrom(address from, address to, uint value) external returns (bool) {
        if (allowance[from][msg.sender] != uint(-1)) {
            allowance[from][msg.sender] = allowance[from][msg.sender].sub(value);
        }
        _transfer(from, to, value);
        return true;
    }

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external {
        require(deadline >= block.timestamp, 'EXPIRED');
        bytes32 digest = keccak256(
            abi.encodePacked(
                '\x19\x01',
                DOMAIN_SEPARATOR,
                keccak256(abi.encode(PERMIT_TYPEHASH, owner, spender, value, nonces[owner]++, deadline))
            )
        );
        address recoveredAddress = ecrecover(digest, v, r, s);
        require(recoveredAddress != address(0) && recoveredAddress == owner, 'INVALID_SIGNATURE');
        _approve(owner, spender, value);
    }
}


// File contracts/test/RouterEventEmitter.sol

pragma solidity =0.6.6;

contract RouterEventEmitter {
    event Amounts(uint[] amounts);

    receive() external payable {}

    function swapExactTokensForTokens(
        address router,
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external {
        (bool success, bytes memory returnData) = router.delegatecall(abi.encodeWithSelector(
            IPancakeRouter01(router).swapExactTokensForTokens.selector, amountIn, amountOutMin, path, to, deadline
        ));
        assert(success);
        emit Amounts(abi.decode(returnData, (uint[])));
    }

    function swapTokensForExactTokens(
        address router,
        uint amountOut,
        uint amountInMax,
        address[] calldata path,
        address to,
        uint deadline
    ) external {
        (bool success, bytes memory returnData) = router.delegatecall(abi.encodeWithSelector(
            IPancakeRouter01(router).swapTokensForExactTokens.selector, amountOut, amountInMax, path, to, deadline
        ));
        assert(success);
        emit Amounts(abi.decode(returnData, (uint[])));
    }

    function swapExactETHForTokens(
        address router,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external payable {
        (bool success, bytes memory returnData) = router.delegatecall(abi.encodeWithSelector(
            IPancakeRouter01(router).swapExactETHForTokens.selector, amountOutMin, path, to, deadline
        ));
        assert(success);
        emit Amounts(abi.decode(returnData, (uint[])));
    }

    function swapTokensForExactETH(
        address router,
        uint amountOut,
        uint amountInMax,
        address[] calldata path,
        address to,
        uint deadline
    ) external {
        (bool success, bytes memory returnData) = router.delegatecall(abi.encodeWithSelector(
            IPancakeRouter01(router).swapTokensForExactETH.selector, amountOut, amountInMax, path, to, deadline
        ));
        assert(success);
        emit Amounts(abi.decode(returnData, (uint[])));
    }

    function swapExactTokensForETH(
        address router,
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external {
        (bool success, bytes memory returnData) = router.delegatecall(abi.encodeWithSelector(
            IPancakeRouter01(router).swapExactTokensForETH.selector, amountIn, amountOutMin, path, to, deadline
        ));
        assert(success);
        emit Amounts(abi.decode(returnData, (uint[])));
    }

    function swapETHForExactTokens(
        address router,
        uint amountOut,
        address[] calldata path,
        address to,
        uint deadline
    ) external payable {
        (bool success, bytes memory returnData) = router.delegatecall(abi.encodeWithSelector(
            IPancakeRouter01(router).swapETHForExactTokens.selector, amountOut, path, to, deadline
        ));
        assert(success);
        emit Amounts(abi.decode(returnData, (uint[])));
    }
}


// File contracts/Migrations.sol

// SPDX-License-Identifier: MIT
pragma solidity >=0.4.25 <0.7.0;

contract Migrations {
  address public owner;
  uint public last_completed_migration;

  modifier restricted() {
    if (msg.sender == owner) _;
  }

  constructor() public {
    owner = msg.sender;
  }

  function setCompleted(uint completed) public restricted {
    last_completed_migration = completed;
  }
}


// File contracts/test/WETH9.sol

// Copyright (C) 2015, 2016, 2017 Dapphub

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity =0.6.6;

contract WETH9 {
    string public name     = "Wrapped Ether";
    string public symbol   = "WETH";
    uint8  public decimals = 18;

    event  Approval(address indexed src, address indexed guy, uint wad);
    event  Transfer(address indexed src, address indexed dst, uint wad);
    event  Deposit(address indexed dst, uint wad);
    event  Withdrawal(address indexed src, uint wad);

    mapping (address => uint)                       public  balanceOf;
    mapping (address => mapping (address => uint))  public  allowance;

    // function() public payable {
    //     deposit();
    // }
    function deposit() public payable {
        balanceOf[msg.sender] += msg.value;
        emit Deposit(msg.sender, msg.value);
    }
    function withdraw(uint wad) public {
        require(balanceOf[msg.sender] >= wad, "");
        balanceOf[msg.sender] -= wad;
        msg.sender.transfer(wad);
        emit Withdrawal(msg.sender, wad);
    }

    function totalSupply() public view returns (uint) {
        return address(this).balance;
    }

    function approve(address guy, uint wad) public returns (bool) {
        allowance[msg.sender][guy] = wad;
        emit Approval(msg.sender, guy, wad);
        return true;
    }

    function transfer(address dst, uint wad) public returns (bool) {
        return transferFrom(msg.sender, dst, wad);
    }

    function transferFrom(address src, address dst, uint wad)
        public
        returns (bool)
    {
        require(balanceOf[src] >= wad, "");

        if (src != msg.sender && allowance[src][msg.sender] != uint(-1)) {
            require(allowance[src][msg.sender] >= wad, "");
            allowance[src][msg.sender] -= wad;
        }

        balanceOf[src] -= wad;
        balanceOf[dst] += wad;

        emit Transfer(src, dst, wad);

        return true;
    }
}


/*
                    GNU GENERAL PUBLIC LICENSE
                       Version 3, 29 June 2007

 Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>
 Everyone is permitted to copy and distribute verbatim copies
 of this license document, but changing it is not allowed.

                            Preamble

  The GNU General Public License is a free, copyleft license for
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                     END OF TERMS AND CONDITIONS

            How to Apply These Terms to Your New Programs

  If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these terms.

  To do so, attach the following notices to the program.  It is safest
to attach them to the start of each source file to most effectively
state the exclusion of warranty; and each file should have at least
the "copyright" line and a pointer to where the full notice is found.

    <one line to give the program's name and a brief idea of what it does.>
    Copyright (C) <year>  <name of author>

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.

Also add information on how to contact you by electronic and paper mail.

  If the program does terminal interaction, make it output a short
notice like this when it starts in an interactive mode:

    <program>  Copyright (C) <year>  <name of author>
    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
    This is free software, and you are welcome to redistribute it
    under certain conditions; type `show c' for details.

The hypothetical commands `show w' and `show c' should show the appropriate
parts of the General Public License.  Of course, your program's commands
might be different; for a GUI interface, you would use an "about box".

  You should also get your employer (if you work as a programmer) or school,
if any, to sign a "copyright disclaimer" for the program, if necessary.
For more information on this, and how to apply and follow the GNU GPL, see
<http://www.gnu.org/licenses/>.

  The GNU General Public License does not permit incorporating your program
into proprietary programs.  If your program is a subroutine library, you
may consider it more useful to permit linking proprietary applications with
the library.  If this is what you want to do, use the GNU Lesser General
Public License instead of this License.  But first, please read
<http://www.gnu.org/philosophy/why-not-lgpl.html>.

*/