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 <bits/stdc++.h> 
using namespace std; 
  
int main() 
{ 
    long long x;
	cin>>x; 
   int  maxvalue = 0; 
    for (int i = 1; i <= x - 2; i++) { 
        for (int j = 1; j <= x - 1; j++) { 
            int k = x - i - j; 
            maxvalue = max(maxvalue, i * j * k); 
        } 
    } 
    double d =(double)maxvalue;
  
  cout<<setprecision(12)<<fixed<<d; 

    return 0; 
}