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: Accepted)

#include<bits/stdc++.h>
 
using namespace std;
typedef unsigned long long int ll;
const ll hell = 100005; 

bool comp( vector<ll> a, vector<ll> b )
{
    return a[0]<b[0];
}
ll binpow(ll a,ll b) 
{
    ll res = 1;
    while (b > 0)
    {
        if (b & 1)
            res*=a;
        a*=a;
        b >>= 1;
    }
    return res;
}
int main()
{   
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    ll s;
    cin>>s;
    double l ,b, h;
    l=s*1.0/3;
    b=(s*1.0 -l)/2.0;
    h=s-l-b;
    cout << fixed << setprecision(6) <<l*b*h;
    return 0;
}