#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint1000000007;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000001


int main(){
	
	double a,b,x,y;
	cin>>a>>b>>x>>y;
	swap(a,x);
	swap(b,y);
	double ok = 0.0,ng = 3e3;
	
	rep(_,60){
		double mid = (ok+ng)/2.0;
		if(mid*(x/(x+y))<=a&&mid*(y/(y+x))<=b)ok=  mid;
		else ng = mid;
	}
	
	cout<<fixed<<setprecision(10)<<ok<<endl;
	
	return 0;
}