#include <bits/stdc++.h>
using namespace std;
int main() {
  long long h, l;
  cin >> h >> l;
  long double k = (long double)(l * l - h * h) / (2 * h);
  std::cout << std::fixed;
  std::cout << std::setprecision(13) << k << '\n';
  return 0;
}
