#include <iostream>
#include <cstring>
#include <stdio.h>
#include <algorithm>
#include <cmath>
#include <map>
#include <vector>
using namespace std;

int main() {
    //freopen("in.txt","r",stdin);
    int T;
    scanf("%d",&T);
    while(T --) {
        int n;
        scanf("%d",&n);
        int val;
        for(int i = 0;i < n;i ++) {
            scanf("%d",&val);
        }
        if(n == 1) {
            printf("%d\n",val);
        }
        else {
            puts("0");
        }
    }
    
}