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

#define int long long
#define ull unsigned long long
#define vi vector<int>
#define vc vector<char>
#define vs vector<string>
#define vb vector<bool>
#define vpii vector<pair<int, int>>
#define vpic vector<pair<int, char>>
#define vpis vector<pair<int, string>>
#define vvi vector<vector<int>>
#define pb push_back
#define pii pair<int, int>
#define rep(i, s, e) for (int i = (s); i < (e); i++)
#define all(x) x.begin(), x.end()
#define fastio ios::sync_with_stdio(false); cin.tie(0);
#define MOD 1000000007

signed main() {
    fastio
    int t;
    cin >> t;
    while(t--) {
        int n, k;
        cin >> n >> k;
        vi a(n);
        int ans = 1;
        rep(i,0, n) {
            cin >> a[i];
            ans *= a[i];
        }
        int maxi = *min_element(all(a));
        ans /= maxi;
        maxi -= k;
        ans *= maxi;
        cout << ans << endl;
    }
}