#include<iostream>
using namespace std;
int arr[2000];
int main()
{
    int T;
    cin >> T;
    for(int i = 0;i < T;i ++)
    {
        int n;
        cin >> n;
        for(int j = 0;j < n;j ++)
            cin >> arr[j];
        if(n == 1)
            cout << arr[0] << endl;
        else
            cout << "0" << endl;
    }
    return 0;
 }