#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <cstring>
#include <vector>
#include <algorithm>
#include <cmath>
using namespace std;


int main()
{
    int T;
    cin >> T;
    while (T--)
    {
        int n;
        cin >> n;
        int g;
        for (int i = 0; i < n; ++i)
            cin >> g;
        if (n == 1) printf("%d\n", g);
        else printf("0\n");
    }

#ifndef ONLINE_JUDGE
    system("pause");
#endif
    return 0;
}