//=================================
// Created on: 2018/09/28 22:46:07
//=================================
#include <bits/stdc++.h>
using ld = long double;
int main()
{
    ld r, d;
    std::cin >> r >> d;
    std::cout << std::fixed << std::setprecision(15) << std::sqrt(d * d - r * r) << std::endl;
    return 0;
}