#include <cstdio>
int main(){
    int n,tt,x;
    scanf("%d",&tt);
    while(tt--){
        scanf("%d",&n);
        for(int i=0;i<n;i++)scanf("%d",&x);
        if(n==1){
            printf("%d\n",x);
        }else{
            printf("0\n");
        }
    }
    return 0;
}