#include<stdio.h>
#include<string.h>
#include<cstdio> 
#include<string>
#include<math.h>
#include<algorithm>
#define LL long long
#define PI atan(1.0)*4
#define DD double
#define MAX 1100
#define mod 100
#define dian 1.000000011
#define INF 0x3f3f3f
using namespace std;
__int64 s[MAX];
LL C(LL n,LL m)
{
    LL ans=1;
    int num=1;
    while(m--)
    {
        ans*=(n-m);
        ans/=num;
        num++;
    }
    return ans;
}
int main()
{
    __int64 n,m,j,i,t,k,sum;
    scanf("%I64d",&t);
    while(t--)
    {
        scanf("%I64d",&n);
        
        for(i=0;i<n;i++)
            scanf("%I64d",&s[i]);
        if(n==1)
        {
            printf("%I64d\n",s[0]);
            continue; 
        }
        if(n==2)
        {
            printf("0\n");
            continue;
        }
        sum=0;
        for(i=0;i<n;i++)
            sum=sum^s[i];
        __int64 ant=0;
        for(i=1;i<=n-1;i++)
            ant+=C(n-1,i);
        ant=ant+1;
        //printf("%lld*\n",ant);
        if(ant%2==0)
            printf("0\n");
        else  
            printf("%I64d\n",sum);
    }
    return 0;
}