#include<stdio.h>
#include<algorithm>
#include<string.h>
using namespace  std;
int com(int n, int r)
{
    if(n - r > r ) r = n - r;
    int i, j, s = 1;
    for(i = 0, j = 1; i < r; ++ i)
    {
        s *= (n-i);
        for(; j <= r && s%j == 0; ++ j) s /= j;
    }
    return s;
}
int main()
{
    int T,n;
    long long a[1005];
    char s[1005];

    while(scanf("%d", &T)!=-1)
    {
        while(T --)
        {
            scanf("%d\n",&n);
            for(int i = 0; i < n; i ++)
            {
                scanf("%d", &a[i]);
            }
            long long cnt = a[0];
            for(int i = 0; i < n; i ++)
            {
                cnt = a[i] & cnt;
            }
            printf("%I64d\n",cnt);
        }
    }
}