#include<bits/stdc++.h>
#define IO ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define pb                          push_back
#define all(x)                      (x).begin(),(x).end()
#define ll                          long long
#define ld                          long double
#define eps                         1e-9
#define sz(a)                       (ll)(a).size()
#define print(ans)                  cout<<(ans?"YES":"NO")<<endl;
#define ppc                         __builtin_popcount
#define ppcll                       __builtin_popcountll
#define endl                        "\n"
#define lb                          lower_bound
#define ub                          upper_bound
const ld PI = 3.141592653589793238462;
const int MOD = 1e9 +7;
const ll INF = 1e18;
// if(abs(a-b)<eps) --> if(a==b)
// fixed << setprecision(n) -->printing decimal till n
// hypot(a ,b) --> sqrt(a^2 + b^2)
using namespace std;

void solve(){
    ll n,x,y,a;
    cin>>n>>x>>y>>a;

    ll total_shampoo =0;
    for(int i=0;i<a;i++){
        ll per;
        cin>>per;
        total_shampoo += per*10;
    }

    ll days_for_summer_break = n*14;
    total_shampoo -= (days_for_summer_break/y)*x;

    if(total_shampoo<0){
        cout<<-1<<endl;
        return;
    }

    ll remi = days_for_summer_break%y;
    if(remi==0 && total_shampoo>=0 && total_shampoo<x){
        cout<<0<<endl;
    }
    else{
        if(total_shampoo<x){
            cout<<-1<<endl;
        }
        else{
            ll ans = (total_shampoo/x)*y - remi;
            cout<<ans<<endl;
        }
    }

}

int main(){
    IO;
    ll t =1;
    cin>>t;
    while(t--){
        solve();
    }
    return 0;
}