#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main() {
    int n;
    cin >> n;

    ll x = 0;
    for (int i = 0; i < n; i++) {
        ll a;
        cin >> a;
        x |= a;
    }

    for (int i = 0;; i++) {
        ll t = 1LL << i;
        if (!(x & t)) {
            cout << t << endl;
            break;
        }
    }

    return 0;
}