#pragma comment(linker, "/STACK:102400000,102400000")
#include <string>
#include <cmath>
#include <iostream>
#include <cstdio>
#include <map>
#include <vector>
#include <algorithm>
#include <set>

using namespace std;

int main() {
    int test, n;
    cin >> test;
    for (int cas = 1; cas <= test; cas++) {
        scanf("%d", &n);
        int a;
        for (int i = 1; i <= n; i++) {
            scanf("%d", &a);
        }
        if (n == 1)
            printf("%d\n", a);
        else
            puts("0");
    }
    return 0;
}