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

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int T; cin >> T;
    while(T--){
        int N,K; cin >> N >> K;
        vector<int> A(N);
        for(auto &a : A) cin >> a;

        long long answer = 1e18;
        for(int i=0; i<N; i++){
            long long now = 1;
            for(int k=0; k<N; k++) now *= A.at(k)-(i==k)*K;
            answer = min(answer,now);
        }
        cout << answer << "\n";
    }

}