#include <bits/stdc++.h>
using namespace std;
long long a[1000000] = {};
int main() {
  cout << fixed;
  long double H, L, x;
  cin >> H >> L;
  cout << setprecision(20);
  long double ans = L * L;
  ans -= H * H;
  ans /= H;
  x = ans / 2.0f;
  cout << x << endl;
  return 0;
}
