#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, L;
  cin >> H >> L;
  long double d =
      ((long double)pow(L, 2) - (long double)pow(H, 2)) / (long double)(2 * H);
  cout << setprecision(15) << d << endl;
  return 0;
}
