#include <bits/stdc++.h>
using namespace std;

int main()
{
	int A, B, X, Y;
	cin >> A >> B >> X >> Y;

	double y = min( (double)X * B / A, (double)Y );
	double x = min( (double)Y * A / B, (double)X );

	cout << fixed << setprecision(12) << x + y << endl;
}