# import sys; input = sys.stdin.buffer.readline
# sys.setrecursionlimit(10**7)
from collections import defaultdict
con = 10 ** 9 + 7; INF = float("inf")

def getlist():
	return list(map(int, input().split()))

#処理内容
def main():
	r, d = list(map(float, input().split()))
	ans = (d ** 2  - r ** 2) ** 0.5
	print(ans)


if __name__ == '__main__':
	main()