e.cpp

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pii;
template <typename T1, typename T2>
ostream &operator <<(ostream &os, pair<T1, T2> p){os << p.first << " " << p.second; return os;}
template <typename T>
ostream &operator <<(ostream &os, vector<T> &v){for(T i : v)os << i << ", "; return os;}
template <typename T>
ostream &operator <<(ostream &os, set<T> s){for(T i : s) os << i << ", "; return os;}
template <typename T1, typename T2>
ostream &operator <<(ostream &os, map<T1, T2> m){for(pair<T1, T2> i : m) os << i << endl; return os;}

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int n; cin >> n;
    ll a[n];
    for(int i = 0; i < n; i++){
        cin >> a[i];   
    }
    ll mval = 0;
    for(int i = 0; i < n; i++){
        for(int j = i; j < n; j++){
            for(int k = j; k < n; k++){
                mval = max(mval, a[i] | a[j] | a[k]);
            }
        }
    }
    cout << mval << endl;
    return 0;
}