#include<bits/stdc++.h>
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define MOD 1000000007
#define gc getchar_unlocked
#define ms(s, n) memset(s, n, sizeof(s))
#define prec(n) fixed<<setprecision(n)
typedef long long ll;
using namespace std;
ll fpow(ll n, ll k, ll p = MOD) {ll r = 1; for (; k; k >>= 1) {if (k & 1) r = r * n%p; n = n * n%p;} return r;}
ll inv(ll a, ll p = MOD) {return fpow(a, p - 2, p);}

int main()
{
    ios::sync_with_stdio(0);
    // cin.tie(0);
    // cout.tie(0);
    ll t;
    cin>>t;
    assert(t>=1 && t<=100);
    while(t--){
        ll n,a[100003],c,d,s;
        cin>>n;
        assert(n>=1 && n<=40000);
        ll maxx=LLONG_MIN;
        for(ll i=0;i<n;i++){
            cin>>a[i];
            assert(a[i]>=1 && a[i]<=1000000000);
            maxx=max(maxx,a[i]);
        }
        sort(a,a+n);
        cin>>c>>d>>s;
        assert(c>=1 && c<=1000000);
        assert(d>=1 && d<=1000000000);
        assert(s>=1 && s<=1000000000);
        cout<<prec(10)<<(c-1)*a[n-1]<<"\n";
    }
}