#include <cmath>
#include <algorithm>
#include <cstdio>
#include <iostream>
#include <cstring>
#include <vector>
#include <queue>
#include <string>
#include <map>
#include <cstdlib>
#include <fstream>
#include <cmath>
#define mem(a,b) memset(a,b,sizeof(a))
using namespace std;
typedef long long ll;
typedef unsigned int ui;
const int maxn=1e4+50;
const int Mod=1e9+7;

int s[maxn];
int main()
{
    #ifndef ONLINE_JUDGE
        freopen("in.txt","r",stdin);
     //   freopen("out.txt","w",stdout);
    #endif
    int T,n;
    scanf("%d",&T);
    while(T--){
        scanf("%d",&n);
        for (int i=0;i<n;i++) scanf("%d",s+i);
        if (n==1) printf("%d\n",s[0]); else printf("%d\n",0);
    }
    return 0;
}