import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

import static java.lang.System.in;

public class No236 {
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(in));
        String[] inputs = reader.readLine().split(" ");
        int A = Integer.parseInt(inputs[0]);
        int B = Integer.parseInt(inputs[1]);
        int X = Integer.parseInt(inputs[2]);
        int Y = Integer.parseInt(inputs[3]);

        System.out.println((A + B) * (float) Math.min(X / ((double) A), Y / ((double) B)));

    }
}