#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <cmath>
#include <map>
#include <string>
#include <sstream>
#include <vector>
#include <queue>

using namespace std;

typedef long long LL;
const int N = 1e3 + 7;
int n, a[N];

int work(int T = 0)
{
    int ans = 0;
    scanf("%d", &n);
    for(int i = 0; i < n; i ++)
        scanf("%d", &a[i]), ans ^= a[i];
    if(n == 1)
        printf("%d\n", ans);
    else
        printf("%d\n", 0);
    return 0;
}

int main()
{
    int T = 0;
    scanf("%d", &T);
    for(int i = 1; i <= T; i ++)
        work(i);
    return 0;
}