#include <bits/stdc++.h>
using namespace std;
void solve() {
  double l, h;
  cin >> h >> l;
  double x = (l * l - h * h) / (2.0 * h);
  cout.precision(15);
  cout << fixed << x << endl;
}
int main() {
  ios_base::sync_with_stdio(false);
  solve();
  return 0;
}
