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

void solve() {
        int N;
        int64_t K;
        cin >> N >> K;
        vector<int64_t> A(N);
        for (auto &x : A) cin >> x;
        int64_t ans = 1LL << 61;
        for (int i = 0; i < N; i++) {
                int64_t curr = 1LL;
                for (int j = 0; j < N; j++) {
                        if (j == i) {
                                curr *= 1LL * (A[j] - K);
                        } else {
                                curr *= 1LL * A[j];
                        }
                }
                ans = min(ans, curr);
        }
        cout << ans << '\n';
}

int main() {
        ios::sync_with_stdio(false);
        cin.tie(NULL);

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

        return 0;
}