#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pll = pair<ll, ll>;
using pii = pair<int, int>;
const int N = 1e6 + 9;
int n, a[N], b[N];
int x, y;
int main() {
  ios_base ::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  double ac, cd;
  cin >> cd >> ac;
  double bc = (0.5 * ((ac * ac) - (cd * cd))) / cd;
  cout << fixed << setprecision(10) << bc << '\n';
}
