#include<iostream>
#include<cstdio>
#include<algorithm>
#define N 100005
using namespace std;
int a[N];
int main()
{
  int t;
  cin>>t;
  while (t--)
  {
   int n,x;
   cin>>n;
   for (int i=1;i<=n;i++)
   {
    scanf("%d",&x);
   }
   if (n>=2) printf("0\n");
   else  printf("%d\n",x);      
  }    
}