#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    
    // X & A[i] == 0
    int N; cin >> N;
    ll X = (1LL << 61) - 1;
    rep(i,N) { ll A; cin >> A; X &= ~A; }
    cout << (X & (-X)) << endl;
}