#include <algorithm>
#include <iostream>
#include <sstream>
#include <cstring>
#include <cstdio>
#include <cstdlib>
#include <vector>
#include <string>
#include <queue>
#include <stack>
#include <cmath>
#include <set>
#include <map>
#define PI 3.1415926
using namespace std;
typedef __int64 ll;
const int inf = 0x3f3f3f3f;
int cmp(const void *a, const void *b)
{
    return *(int*)a - *(int*)b;
}
int ans;
void fullCombination(int num[], int rcd[], int cur, int begin, int n)
{
    int i;
    for(i=0; i<cur; ++i)
    {
        ans^=rcd[i];
    }
    for(i=begin; i<n; ++i)
    {
        rcd[cur] = num[i];
        fullCombination(num, rcd, cur+1, i+1, n);
    }
}
int a[1010],rcd[1010];
int main()
{
    //freopen("D://in.txt","r",stdin);
    int T,n;
    scanf("%d",&T);
    while(T--)
    {
        scanf("%d",&n);
        for(int i=0;i<n;i++)
        {
            scanf("%d",&a[i]);
        }
        if(n==1)
            printf("%d\n",a[0]);
        else
            printf("0\n");
        /*qsort(a, n, sizeof(a[0]), cmp);
        ans=0;
        fullCombination(a, rcd, 0, 0, n);
        printf("%d\n",ans);*/
    }
}