#include <iostream>
#include <vector>
#include <algorithm>
#include <atcoder/segtree>
#include <atcoder/lazysegtree>
using namespace std;
using i32 = int32_t;
using u32 = uint32_t;
using i64 = int64_t;
using u64 = uint64_t;
#define rep(i,n) for(int i=0; i<(n); i++)


namespace RQ{
  using S = int;
  S e(){ return 1000000000; };
  S op(S l, S r){ return 1000000000; };
  using F = int;
  S mapping(F f, S x){ if(f == -1) return x; return f; }
  F composition(F f, F x){ if(f == -1) return x; return f; }
  F id(){ return -1; }
  using RQ = atcoder::lazy_segtree<S,op,e,F,mapping,composition,id>;
}
namespace RMQ{
  using S = int;
  S e(){ return 1000000000; };
  S op(S l, S r){ return min(l,r); };
  using RQ = atcoder::segtree<S,op,e>;
}


struct Query{ int l,r,q; };


int main(){
  int N; cin >> N;
  u64 ans = ~(u64)0;
  rep(i,N){
    u64 a; cin >> a;
    ans &= ~a;
  }
  ans = ans & -ans;
  cout << ans << endl;
  return 0;
}




struct ios_do_not_sync {
    ios_do_not_sync() {
        ios::sync_with_stdio(false);
        cin.tie(nullptr);
    }
} ios_do_not_sync_instance;