diff --git a/lib.js b/lib.js
index 60f30ab..e2362ec 100644
--- a/lib.js
+++ b/lib.js
@@ -7,9 +7,84 @@
  * @param {Filter} filter
  */
 function Iterator(friends, filter) {
-    console.info(friends, filter);
+    if (!Filter.prototype.isPrototypeOf(filter)) {
+        throw new TypeError('Wrong type of filter. It must be Filter');
+    }
+    this.friendsWithLevel = this.friendsLevel(friends).filter(function (friend) {
+        return filter.condition(friend.friend);
+    });
+
+    this.currentFriend = 0;
 }
 
+Iterator.prototype.friendsLevel = function (friends) {
+    var bestFriends = friends.filter(function (friend) {
+        return friend.hasOwnProperty('best') && friend.best;
+    });
+
+    var namesOfFriends = [];
+    var friendsWithLevel = [];
+    bestFriends.forEach(function (friend) {
+        namesOfFriends.push(friend.name);
+        friendsWithLevel.push(
+            {
+                friend: friend,
+                level: 1
+            }
+        );
+    });
+
+    for (var i = 0; i < friendsWithLevel.length; i++) {
+        var newLevelFriends =
+        friendsWithLevel[i].friend.friends.reduce(function (newLevelFunction, friendName) {
+            if (namesOfFriends.indexOf(friendName) === -1) {
+                var friendToPush = friends.filter(function (friend) {
+                    return friend.name === friendName;
+                });
+                newLevelFunction = newLevelFunction.concat(friendToPush);
+            }
+
+            return newLevelFunction;
+        }, []);
+        for (var j = 0; j < newLevelFriends.length; j++) {
+            friendsWithLevel.push(
+                {
+                    friend: newLevelFriends[j],
+                    level: friendsWithLevel[i].level + 1
+                }
+            );
+            namesOfFriends.push(newLevelFriends[j].name);
+        }
+    }
+
+    friendsWithLevel.sort(function (friendOne, friendTwo) {
+        if (friendOne.level > friendTwo.level) {
+            return 1;
+        }
+        if (friendOne.level < friendTwo.level) {
+            return -1;
+        }
+
+        return (friendOne.friend.name > friendTwo.friend.name) ? 1 : -1;
+    });
+
+    return friendsWithLevel;
+};
+
+
+Iterator.prototype.next = function () {
+    if (this.currentFriend === this.friendsWithLevel.length) {
+        return null;
+    }
+
+    return this.friendsWithLevel[this.currentFriend++].friend;
+};
+
+Iterator.prototype.done = function () {
+    return this.currentFriend === this.friendsWithLevel.length;
+};
+
+
 /**
  * Итератор по друзям с ограничением по кругу
  * @extends Iterator
@@ -19,15 +94,22 @@ function Iterator(friends, filter) {
  * @param {Number} maxLevel – максимальный круг друзей
  */
 function LimitedIterator(friends, filter, maxLevel) {
-    console.info(friends, filter, maxLevel);
+    Iterator.call(this, friends, filter);
+    this.friendsWithLevel = this.friendsWithLevel.filter(function (friend) {
+        return maxLevel >= friend.level;
+    });
 }
 
+LimitedIterator.prototype = Object.create(Iterator.prototype);
+
 /**
  * Фильтр друзей
  * @constructor
  */
 function Filter() {
-    console.info('Filter');
+    this.condition = function () {
+        return true;
+    };
 }
 
 /**
@@ -36,18 +118,26 @@ function Filter() {
  * @constructor
  */
 function MaleFilter() {
-    console.info('MaleFilter');
+    this.condition = function (friend) {
+        return friend.gender === 'male';
+    };
 }
 
+MaleFilter.prototype = Object.create(Filter.prototype);
+
 /**
  * Фильтр друзей-девушек
  * @extends Filter
  * @constructor
  */
 function FemaleFilter() {
-    console.info('FemaleFilter');
+    this.condition = function (friend) {
+        return friend.gender === 'female';
+    };
 }
 
+FemaleFilter.prototype = Object.create(Filter.prototype);
+
 exports.Iterator = Iterator;
 exports.LimitedIterator = LimitedIterator;