import java.util.Scanner;

public class No236 {
	public static void main(String[] args) {
		Scanner sc= new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int x = sc.nextInt();
		int y = sc.nextInt();
		sc.close();
		double work1, work2;
		work1 = (double)x * (a + b) / a;
		work2 = (double)y * (a + b) / b;
		double en_ou_tya;
		if(work1 > work2){
			en_ou_tya = work2;
		}else{
			en_ou_tya = work1;
		}
		System.out.println(en_ou_tya);
	}
}