# -*- coding: utf-8 -*-
# !/usr/bin/env python
# vim: set fileencoding=utf-8 :

"""
#
# Author:   Noname
# URL:      https://github.com/pettan0818
# License:  MIT License
# Created: 金  9/28 21:30:32 2018

# Usage
#
"""
import math
def get():
    return [float(i) for i in input().split(' ')]

def solve(in_list):
    """
    >>> solve([3.000000,5.000000])
    >>> solve([123.456789,123.456790])
    """
    d = in_list[0]
    r = in_list[1]

    return math.sqrt(r*r-d*d)

if __name__ == '__main__':
    print(solve(get()))