#include<cstdio>
#include<cmath>
#include<iostream>
#include<cstring>
#include<algorithm>
#include<string>
#include<stack>
#include<queue>
#include<map>
#include<utility>
#pragma comment(linker, "/STACK:102400000,102400000")
using namespace std;
const int MN=300+10;
const int ME=100000+10;
const int MOD=1e9+7;
typedef long long LL;
typedef unsigned long long ULL;
const double pi=acos(-1.0);
const int Intmax=(~(1<<31));
const int Intmin=(1<<31);
const LL LLmax=(~(1LL<<63));
const LL LLmin=(1LL<<63);
const ULL ULLmax=(~(0ULL));
typedef long long LL;
int main(){
#ifndef ONLINE_JUDGE
    freopen("1.cpp","r",stdin);
#endif // ONLINE_JUDGE
    int t;
    scanf("%d",&t);
    while(t--){
        int n;
        scanf("%d",&n);
        int ans=0;
        if(n==1){
            int x;
            scanf("%d",&x);
            ans^=x;
            printf("%d\n",ans);
        }
        else{
            while(n--){
                int x;
                scanf("%d",&x);
            }
            printf("0\n");
        }
    }
    return 0;
}