#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <utility>
#include <string>

using namespace std;

int main() {
	int a, b, x, y;

	cin >> a >> b >> x >> y;

	double k = min(1.0 * x / a, 1.0 * y / b);
	double ans = k * (a + b);
	printf("%.9f\n", ans);
	return 0;
}