#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define vll vector<ll>
#define vi vector<int>
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()



void solve() {
   ll n,k;cin>>n>>k;
   vll v(n);
   for(auto &a:v) cin>>a;
   sort(all(v));
   v[0] = v[0]-k;
   ll ans = 1;
   for(auto a:v) ans *=a;
   cout<<ans<<endl;
}

int main() {
    int t = 1;
    cin>>t;
    while (t--) solve();
}