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;

#define fast_cin() ios_base::sync_with_stdio(false);cin.tie(NULL)
#define reP(i, x, n) for(int i=x; i<n; i++)
#define aLL(x) x.begin(), x.end()
#define pB push_back
#define eB emplace_back
#define tRav(a, x) for(auto& a: x)
#define fI first
#define sE second
#define lB lower_bound
#define uB upper_bound
#define MOD 1000000007

typedef vector<int> vec;
typedef long long ll;
typedef unsigned long long ull;

bool isPalindrome(string str) 
{ 
    int l = 0;
    int h =str.length() - 1; 
  
    while (h > l) 
    { 
        if (str[l++] != str[h--]) 
        { 
            return false; 
        } 
    } 
   return true; 
} 


int main(){
    fast_cin();
    double l;cin>>l;
    double x=l/3;
    //cout<<x<<endl;
    double ans = x*x*x;
    printf("%0.12f\n", ans);

}