#include<iostream>
using namespace std;

int main() {
    int T;
    int a;
    cin >> T;
    while (T--) {
        int n;
        cin >> n;
        for (int i = 1; i <= n; i++) {
            cin >> a;
        }
        if (n == 1) {
            cout << a << endl;
            continue;
        }
        cout << "0" << endl;
    }
    return 0;
}