#include <iostream>
using namespace std;
// It is difficult
int main(void){
    int t;
    cin >> t;
    while(t--){
        int N, K;
        cin >> N >> K;
        long long A[10];
        for (int i = 0; i < N; i++){
            cin>>A[i];
        }
        long long product = 1;
        A[0] = A[0] - K;
        for(int i = 0; i < N; i++){
            product = product * A[i];
        }
        cout << product << endl;
    }
    return 0;
}