import java.util.Scanner;

public class Main{
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		while(sc.hasNext()){
			double a=sc.nextDouble();
			double b=sc.nextDouble();
			double x=sc.nextDouble();
			double y=sc.nextDouble();
			System.out.println(Math.min(x*(a+b)/a,y*(a+b)/b));
		}
	}
}