#include<bits/stdc++.h>
using namespace std;
using Int = long long;

struct Precision{
  Precision(){
    cout<<fixed<<setprecision(12);
  }
}precision_beet;

//INSERT ABOVE HERE
signed main(){
  double a,b,x,y;
  cin>>a>>b>>x>>y;
  double l=0,r=1e9;
  for(Int k=0;k<200;k++){
    double m=(l+r)/2;
    if(m/(a+b)*a<=x&&m/(a+b)*b<=y) l=m;
    else r=m;
  }
  cout<<l<<endl;
  return 0;
}