Problem:
Score : 300 points

Problem Statement

Given is a positive integer L.
Find the maximum possible volume of a rectangular cuboid whose sum of the dimensions (not necessarily integers) is L.

Constraints

1 ≤ L ≤ 1000

L is an integer.

Input

Input is given from Standard Input in the following format:

L

Output

Print the maximum possible volume of a rectangular cuboid whose sum of the dimensions (not necessarily integers) is L.
Your output is considered correct if its absolute or relative error from our answer is at most 10^{-6}.

Sample Input 1

3

Sample Output 1

1.000000000000

For example, a rectangular cuboid whose dimensions are 0.8, 1, and 1.2 has a volume of 0.96.

On the other hand, if the dimensions are 1, 1, and 1, the volume of the rectangular cuboid is 1, which is greater.

Sample Input 2

999

Sample Output 2

36926037.000000000000

Solution in Python (3.4.3) (judge verdict: Wrong Answer)

l = int(input())

ans = 0
if l >= 3:
    for i in range(l):
        if (l - i) % 2 == 0:
            a = (l - i) / 2
            b = (l - i) / 2
        else:
            a = ((l - i) / 2)
            b = (l - i) / 2
        ans = max(ans, a * b * i)
else:
    i = 0
    while i < l:
        if (l - i) % 2 == 0:
            a = (l - i) / 2
            b = (l - i) / 2
        else:
            a = ((l - i) / 2)
            b = (l - i) / 2
        ans = max(ans, a * b * i)
        i += 0.1

print(ans)