#include <bits/stdc++.h>
using namespace std;
long long int mod = 1e9 + 7, test;
long long int max(long long int a, long long int b) { return a > b ? a : b; }
long long int min(long long int a, long long int b) { return a > b ? b : a; }
void solve() {
  long long int A, L;
  cin >> A >> L;
  long double a = (long double)A, l = (long double)L;
  long double h = l * l - a * a;
  h /= (2 * a);
  cout << fixed;
  cout << setprecision(7);
  cout << h;
  printf("\n");
}
int main() {
  long long int t = 1;
  solve();
  return 0;
}
