#include <cstdio>
#include <iostream>
#include <cstring>
#include <string>
#include <cstdlib>
#include <algorithm>
#include <cmath>
#include <vector>
#include <set>
#include <list>
#include <queue>
#include <map>
#include <stack>
using namespace std;
#define L(i) i<<1
#define R(i) i<<1|1
#define INF  0x3f3f3f3f
#define pi acos(-1.0)
#define eps 1e-3
#define maxn 100010
#define MOD 1000000007

int n,m;
int dp[110][110];
int a[1010],sum[110];

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