#include <bits/stdc++.h>
using namespace std;
const int N = 1e6 + 5, MOD = 1e9 + 7;
signed main() {
  long double H, L;
  cin >> H >> L;
  long double ans = (L * L - H * H) / (2 * H);
  cout << setprecision(9) << fixed << ans;
}
