#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<string>
#include<map>
#include<set>
#include<vector>
#include<cassert>
#define LL long long
#define LD double
#define inf 10000000000000000ll
using namespace std;
int a[2000100];
int main()
{
    int t;scanf("%d",&t);
    while (t--)
    {
        int n;scanf("%d",&n);
        for (int i=1;i<=n;i++) scanf("%d",&a[i]);
        if (n==1) printf("%d\n",a[1]);else printf("0\n");
    }
}