#include<bits/stdc++.h>

using namespace std;
using ll=long long;

int min(vector<int> &A){
    int res = A[0];
    for (int a: A) {
        if (a < res) res = a;
    }

    return res;
}

ll prod(vector<int> &A){
    ll res = 1;
    for (int a: A) res *= a;
    return res;
}

ll solve(){
    int N, K; cin >> N >> K;
    vector<int> A(N);
    for (int i = 0; i < N; i ++) cin >> A[i];
    return prod(A) / min(A) * (min(A) - K);
}

int main(){
    int T; cin >> T;
    for (int t = 1; t <= T; t ++) cout << solve() << endl;
    return 0;
}