#include <iostream>
#include<stdio.h>
#include<string.h>
#include<stack>
#include<algorithm>
#include<sstream>
#include<vector>
using namespace std;

#define maxn 10000
#define ll __int64
int  f[maxn];
int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {
        int n;
        scanf("%d",&n);
        for(int i=0;i<n;i++)
        {
            scanf("%d",&f[i]);
        }
        if(n==1) printf("%d\n",f[0]);
        else printf("0\n");
    }
}