#include <algorithm>
#include <iostream>
#include <sstream>
#include <cstring>
#include <cstdlib>
#include <string>
#include <vector>
#include <cstdio>
#include <cmath>
#include <queue>
#include <stack>
#include <map>
#include <set>
using namespace std;
#define INF 0x3f3f3f3f
const int N=200005;
const int mod=1e9+7;

int n,m,t,a[1005];

int main() {
    cin>>t;
    while (t--) {
        cin>>n;
        for (int i=0; i<n; i++) {
            scanf("%d",&a[i]);
        }
        if (n==1) {
            cout<<a[0]<<endl;
        } else cout<<"0"<<endl;
    }
    return 0;
}