#include <bits/stdc++.h>

using i64 = long long;
using u64 = unsigned long long;
using u32 = unsigned;
using u128 = unsigned __int128;

using F = long double;

void solve() {
    int N, M;
    std::cin >> N >> M;
    
    F A, B;
    std::cin >> A >> B;
    
    std::vector<F> x(N);
    for (int i = 0; i < N; i++) {
        std::cin >> x[i];
    }
    
    std::sort(x.begin(), x.end());
    
    std::vector<F> pre(N + 1);
    for (int i = 0; i < N; i++) {
        pre[i + 1] = pre[i] + x[i];
    }
    
    auto get = [&](F a, F b) {
        a -= 1;
        
        if (a == 0) {
            return std::abs(b) * N;
        }
        
        F ans = 0;
        
        int k = std::lower_bound(x.begin(), x.end(), -b / a) - x.begin();
        ans += std::abs(a * pre[k] + b * k);
        ans += std::abs(a * (pre[N] - pre[k]) + b * (N - k));
        return ans;
    };
    
    for (int i = 0; i < M; i++) {
        F c, d;
        std::cin >> c >> d;
        
        F ans = get(A * c, B * c + d) + get(c * A, d * A + B);
        std::cout << ans << "\n";
    }
}

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    
    std::cout << std::fixed << std::setprecision(10);
    
    int t;
    std::cin >> t;
    
    for (int i = 1; i <= t; i++) {
        std::cout << "Case " << i << ":\n";
        solve();
    }
    
    return 0;
}