n  = [list(map(int, s.split())) for s in open(0)][0][0]

c = n / 3

print((c ** 3))
def main():

    n = int(eval(input()))

    print(((n/3)**3))





if __name__ == "__main__":

    main()

n = [list(map(int, s.split())) for s in open(0)][0][0]
c = n / 3
print((c**3))

def main():
    n = int(eval(input()))
    print(((n / 3) ** 3))


if __name__ == "__main__":
    main()

-n = [list(map(int, s.split())) for s in open(0)][0][0] -c = n / 3 -print((c**3)) +def main(): +    n = int(eval(input())) +    print(((n / 3) ** 3)) + + +if __name__ == "__main__": +    main()