#include <bits/stdc++.h>
using namespace std;
int main() {
  long double h, l;
  cin >> h >> l;
  long double x = 0, ll, hh;
  ll = l * l;
  hh = h * h;
  x = (ll - hh) / (2 * h);
  cout << setprecision(13) << x;
}
