#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 r,d;
  cin>>r>>d;
  cout<<sqrt(d*d-r*r)<<endl;
  return 0;
}