#include <stdio.h>

int main(void){
	int a,b,x,y;
	
	double div;
	double l, r;
	double ans;
	scanf("%d %d %d %d", &a, &b, &x, &y);
	
	l = 1.0*x/a;
	r = 1.0*y/b;
	
	if(l < r){
		div = l;
	}else{
		div = r;
	}
	
	ans = (1.0*a*div) + (1.0*b*div);
	
	printf("%.10f\n", ans);
	return 0;
}