#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef string str;
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    ll t;
    cin >> t;
    cout << fixed << setprecision(0);
    while (t--)
    {
        ll n, k;
        cin >> n >> k;
        ll a[n];
        for (ll i = 0; i < n; i++) cin >> a[i];
        sort(a, a + n);
        a[0] -= k;
        ll sum = 1;
        for (ll i = 0; i < n; i++) sum *= a[i];
        cout << sum << "\n";
    }
    return 0;
}