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: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;

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

            decimal a = 0;
            decimal b = 0;
            decimal c = 0;

            decimal hoge = L;

            if (L % 3 == 0) {

            } else if (L % 3 == 1) {
                hoge -= 1m;
                //Console.WriteLine("mod 1");
            } else if (L % 3 == 2) {
                hoge -= 2m;
            }


            a = b = c = hoge / 3;


            if (L % 3 == 0) {

            } else if (L % 3 == 1) {
                a += 1m;
                //Console.WriteLine("mod 1");
            } else if (L % 3 == 2) {
                a += 1m;
                b += 1m;
            }



            decimal ans = a * b * c;

            Console.WriteLine(ans);
        }

    }

}