#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;

#define ll long long
#define rep(i, n) for (int i = 0; i < (n); i++)
#define P pair<int, int>
#define LP pair<ll, ll>
#define fi first
#define se second
#define pb push_back
#define eb emplace_back
#define all(s) s.begin(), s.end()
#define rall(s) s.rbegin(), s.rend()
template<class T>
void chmax(T& a, T b) { a = max(a, b); };
template<class T>
void chmin(T& a, T b) { a = min(a, b); };

int main() {
  int n;
  cin >> n;
  ll tot = 0;
  rep(i,n) {
    ll a;
    cin >> a;
    tot |= a;
  }
  int j = 0;
  while (true) {
    if (tot>>j&1) {
      j++;
      continue;
    }
    ll ans = (1ll<<j);
    cout << ans << endl;
    return 0;
  }

  return 0;
}