#include <bits/stdc++.h>
using namespace std;
int main(){
  int N;
  cin >> N;
  vector<long long> A(N);
  for (int i = 0; i < N; i++){
    cin >> A[i];
  }
  long long S = 0;
  for (int i = 0; i < N; i++){
    S |= A[i];
  }
  for (int i = 1; i <= 60; i++){
    if ((S >> i & 1) == 0){
      cout << ((long long) 1 << i) << endl;
      break;
    }
  }
}