#include <bits/stdc++.h>
using namespace std;
long long z = 1000000000 + 7;
long long bexp(long long a, long long b) {
  if (b == 0) return 1;
  if (b == 1) return a;
  long long r = bexp(a, b / 2);
  r = r * r;
  if (b % 2 == 0)
    return r;
  else
    return a * r;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int t = 1;
  while (t--) {
    long double n, ans = 0, i, j = 0, p = 0, l = 0, sum = 0, k, cnt = 0, m,
                   q = 0, r = 0, c, y = 0;
    cin >> p >> q;
    ans = (q * q - p * p) / (2 * p);
    cout << fixed << setprecision(14) << ans;
  }
  return 0;
}
