#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); ++i)

using std::cin;
using std::cout;
using std::vector;
using ll = long long;

int main() {
	int n;
	cin >> n;
	
	vector<ll> a(n);
	rep(i, n) cin >> a[i];
	
	ll s = 0;
	rep(i, n) s |= a[i];
	
	rep(i, 61) {
		if ((s >> i & 1) == 0) {
			cout << (1ll << i) << '\n';
			break;
		}
	}
	
	return 0;
}