#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];
	long long ans;
	for( int i = 0; i < 63; i++ ) {
		ans = 1LL << i;
		if( (ans & s ) == 0 ) break;
	}

	cout << ans << endl;
}