#include<bits/stdc++.h>
using namespace std;
const int N=2e5+5;
int T,n,vis[65];long long k,x,lst; 
void solve(){bool fl=0;
	memset(vis,-1,sizeof(vis));
	scanf("%d%lld%lld",&n,&k,&lst);
	for(int i=2;i<=n;i++){
		scanf("%lld",&x);
		for(int j=60;j>=0;j--)if((x>>j)!=(lst>>j)){
			if(vis[j]!=-1&&((x>>j)&1)!=!vis[j])fl=1;
			vis[j]=!((x>>j)&1);
//			cout<<i<<" "<<j<<endl;
			break ;
		}
		lst=x;
	}
	long long sum=0;
	if(fl)return puts("0"),void();
	for(int i=60;i>=0;i--){
//		cout<<vis[i]<<endl;
		if(((k>>i)&1)&&(vis[i]==-1||!vis[i])){
			long long s=1;
			for(int j=0;j<i;j++)if(vis[j]==-1)s*=2;
			sum+=s; 
		}
		if(vis[i]!=-1&&vis[i]!=((k>>i)&1))break ;
	}
	printf("%lld\n",sum);
}
int main(){
	scanf("%d",&T);
	while(T--)solve(); 
	return 0;
}