#include <bits/stdc++.h>
using namespace std;
int A, B, X, Y;
int main() {
	cin >> A >> B >> X >> Y;
	cout << fixed << setprecision(15) << min(1.0 * X / A * (A + B), 1.0 * Y / B * (A + B)) << endl;
	return 0;
}