#include <bits/stdc++.h>
using namespace std;
int n, m;
int t;
double h, l;
int main() {
  cin >> h >> l;
  long long a, b, c;
  a = l * l;
  b = h * h;
  c = a - b;
  double ans = (double)c;
  printf("%.13f\n", ans / 2 / h);
}
