import sys
input = sys.stdin.readline

def linput():
	return list(map(float,input().split()))

def gcd(a: int, b: int):
	while b: a, b = b, a%b
	return a

def lcm(a: int, b: int):
	return a * b // gcd(a, b)

def main():
	A,B = linput()
	E = 10**(-6)
	
	res = 0.0
	T = (A+B)/2
	res -= (1/3) * B**3 + (A-T) * B**2
	res += (1/3) * A**3 + (B-T) * A**2
	
	print(res)

if __name__ == "__main__":
	main()