#include<bits/stdc++.h>

using namespace std;

const int N = 110;

typedef unsigned long long ull;

int n;
ull a[N];

int main()
{
    int n;
    scanf("%d",&n);
    ull x = 0;
    for(int i = 0;i < n;i ++ ) scanf("%llu",&a[i]), x |= a[i];
    int t = 0;
    for(int i = 0;i <= 64;i ++ )
    {
        if(((x >> i) & 1) == 0)
        {
            t = i;
            break;
        }
    }
    printf("%llu\n",1ull << t);
}