#include <bits/stdc++.h>
void answer(double v) { std::cout << std::fixed << v << '\n'; }
void solve(unsigned h, unsigned l) {
  answer((1ull * l * l - 1ull * h * h) / 2.0 / h);
}
int main() {
  unsigned h, l;
  std::cin >> h >> l;
  solve(h, l);
  return 0;
}
