#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using ld = long double;

int main() {
  double r, d; cin >> r >> d;
  double x = sqrt(d * d - r * r);
  cout << fixed << setprecision(15) << x << endl;
  return 0;
}