#include <iostream>
#include <vector>
using namespace std;
using ll = long long;

int main(){
    int n; cin >> n;
    vector<ll> a(n);
    for(auto &it: a) cin >> it;
    for(int i = 0; i < 62; i++){
        bool isok = true;
        for(auto &it: a){
            if((it >> i) & 1) isok = false;
        }
        if(isok){
            cout << (1LL << i) << endl;
            return 0;
        }
    }
    return 0;
}