#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
using namespace std;
void subMain() {
  double a, b;
  cin >> a >> b;
  cout << fixed << (b * b - a * a) / (2 * a);
}
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  subMain();
  cerr << "Time : " << 1000 * ((double)clock()) / (double)CLOCKS_PER_SEC
       << "ms\n";
  return 0;
}
