#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <cstring>
#include <string>
#include <algorithm>
#include <cmath>
using namespace std;
const int Maxn=1005;
int T,n,ans;
int a[Maxn];
int main()
{   //freopen("A.in","r",stdin);
    //freopen("A.out","w",stdout);
    int i,j;
    scanf ("%d",&T);
    while(T--)
    {
        scanf ("%d",&n);
        ans=0;
        for (i=1;i<=n;i++)
            scanf ("%d",&a[i]),a[i]^=a[i-1];
        if (n==1) ans=a[1];
        else ans=0;
        cout<<ans<<endl;
    }
    return 0;
}