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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;

namespace ABC159c
{
    class Program
    {
        static void Main(string[] args)
        {
            int L = int.Parse(Console.ReadLine());

            int w = (int)(L / 3);

            double max = 0;
            for (double i = w; i < w+1; i=i+0.001)
            {
                for (double j = w; j < w+1; j=j+0.001)
                {
                    double d = L - i - j;
                    double v = i * j * d;
                    if(max < v)
                    {
                        max = v;
                    }
                }
            }

            Console.WriteLine(max);
        }
    }
}