// No.236 鴛鴦茶
// https://yukicoder.me/problems/no/236
//

#include <iostream>
#include <cmath>
#include <algorithm>
#include <iomanip>
using namespace std;

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    long double A, B, X, Y;
    cin >> A >> B >> X >> Y;

    long double coffee_limit =  X * (A + B) / A;
    long double tea_limit = Y * (A + B) / B;
    cout << setprecision(12) << min(coffee_limit, tea_limit) << endl;
}