#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;

int main() {
    int t;
    scanf("%d", &t);
    while(t--) {
        int n, num;
        scanf("%d", &n);
        for(int i = 1; i <= n; i++) scanf("%d", &num);
        if(n == 1) printf("%d\n", num);
        else printf("0\n");
    }
    return 0;
}