#include<stdio.h>
#include<string.h>
const int MAX=1005;
int a[MAX];
int main()
{
    int t,n,sum;
    long long ans;
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d",&n);
        memset(a,0,sizeof(a));
        for(int i=0;i<n;i++)
        scanf("%d",&a[i]);
        ans=0;
        if(n==1)printf("%d\n",a[0]);
        else printf("0\n");
    }
}