#include<bits/stdc++.h>
using namespace std;
 
#define quick() ios_base::sync_with_stdio(false); cin.tie(0);
#define pb push_back
 
int mod=1000000007;
 
 
int main(){
    int t;cin>>t;
    while(t--){
        int n,x;cin>>n>>x;
        int a[n];
        for(int &x:a) cin>>x;
        sort(a,a+n,greater<int>());
        int ok=0;
        for(int i=0;i<n;i++){
        	for(int j=i+1;j<n;j++){
        		if(a[i]-a[j]==x){
        			cout<<1;ok=1;
        			break;
				}
			}
		}
		if(!ok) cout<<-1;
    	cout<<endl;
	}
}

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Mgo2IDc4CjUgMjAgMyAyIDUgODAKNSA0NQo5MCA3MCAyMCA4MCA1MA==

2
6 78
5 20 3 2 5 80
5 45
90 70 20 80 50