#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
using namespace std;
const long long mod=1e9+7;
int main()
{

    int t,n,a[1004];
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d",&n);
        for(int i=1;i<=n;i++)
        {
            scanf("%d",&a[i]);
        }
        if(n==1)
        {
            cout<<a[1]<<"\n";
        }
        else cout<<"0"<<"\n";
    }
    return 0;
}