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++ (GCC 9.2.1) (judge verdict: Wrong Answer)

# include<bits/stdc++.h>
#define ll long long
#define pb push_back
#define pf push_front
#define in freopen( "input.txt" , "r" , stdin );
#define out freopen( "output.txt" , "w" , stdout );

using namespace std ;

int N2 = 2 * ( 1e5 + 7 ) ;

ll N1 = 1e7 + 7 ;

int main( ){

    // in

    // out

    int n ;

    cin >> n ;

    int u = n / 3 ;

    int y = n % 3 ;

    int h = u + y ;

    int r = ( u * u ) * h ;

    cout<< r << ".000000" << endl ;


}