#include <bits/stdc++.h>

#define EPS (1e-7)
#define INF (1e9)
#define LINF (1e18)
#define PI (acos(-1))
#define MOD 1000000007
#define MAX 100000

using namespace std;
typedef long long ll;

int main()
{
  double r, d;
  cin >> r >> d;

  cout << fixed << setprecision(10) << sqrt(d*d - r*r) << endl;
}