#ifdef ONPC
#define _GLIBCXX_DEBUG
#endif
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<ll> vi;
typedef vector<vector<ll>> vvi;
typedef vector<pair<ll,ll>> vpi;
typedef pair<ll,ll> pi;
#define F first
#define S second
#define PB push_back
#define MP make_pair
#define popcount __builtin_popcountll
#define forn(i,a,b) for (ll i = a; i < b; i++)

void solve(){
    ll n,k;cin>>n>>k;
    vi arr(n);
    forn(i,0,n)cin>>arr[i];
    sort(arr.begin(),arr.end());
    if(arr[0]<=k){
    	cout<<0<<"\n";
    	return;
    }
    else{
    	ll product=arr[0]-k;
    	forn(i,1,n){
    		product*=arr[i];
    	}
    	cout<<product<<"\n";
    }
}

signed main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    ll t=1;
    cin >> t;
    forn(i,0,t){
        solve();
    }
    #ifdef ONPC
    cerr << endl
         << "finished in " << clock() * 1.0 / CLOCKS_PER_SEC << " sec" << endl;
    #endif
}