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++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <iostream>
#include <iomanip>

using namespace std;

int main(void){

  int L;
  double tate, yoko, takasa;
  double V;
  double m = 0;

  cin >> L;

  for(double i=0.01; i<=L/3*2-0.01; i+=0.01){
    tate = i;
    yoko = L/3;
    takasa = L/3*2 - i;
    // cout << tate << " " << yoko << " " << takasa << " ";
    V = tate * yoko * takasa;
    if(m<V) m = V;
    // cout << m << endl;
  }

  cout << setprecision(10) << m << endl;

  return 0;
}