#include <bits/stdc++.h>
using namespace std;
int main() {
  double dip;
  double ht, len;
  cin >> ht >> len;
  dip = (len * len - ht * ht);
  dip = dip / (2 * ht);
  cout << fixed << setprecision(6) << dip << endl;
  return 0;
}
