#include <bits/stdc++.h>
using namespace std;

int t, k, n, a[10];

long long cal_cost(int a[], int n) {
	long long Answer = 1;
	for (int i = 1; i <= n; i++) {
		Answer *= a[i];
	}
	return Answer;
}

int main() {
	cin >> t;
	for (int i = 1; i <= t; i++) {
		cin >> n >> k;
		for (int j = 1; j <= n; j++) cin >> a[j];
		long long ans = 1'000'000'000'000'000'000LL;
		for (int j = 1; j <= n; j++) {
			a[j] -= k;
			ans = min(ans, cal_cost(a, n));
			a[j] += k;
		}
		cout << ans << endl;
	}
	return 0;
}