#include<iostream>
#include<vector>
#include <bits/stdc++.h>
using namespace std;
#define int long long
void solve(){
int n,k;
cin>>n>>k;
int product=1;
vector<int>a(n);
for(int i=0;i<n;i++){
    cin>>a[i];
    product*=a[i];
}
int mini=product;

int ans;
for(int i=0;i<n;i++){
    ans=1;
    int cost=a[i]-k;
    for(int j=0;j<n;j++){
        if(i==j){
            ans*=cost;
        }else{
        ans*=a[j];
        }
    }
    mini=min(mini,ans);
}
cout<<mini<<endl;
}

int32_t main(){
   int t;cin>>t;
   while(t--)
    solve();

}