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 <algorithm>
#include <cstring>
#include <iostream>
#include <vector>
#include <cmath>
#include <math.h>
#include <stdio.h>
#include <iomanip>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <string>
#define rep(i,n) for (int i = 0; i < (n); ++i)

using namespace std;
const int MOD = 1000000007;


typedef long long int ll; 
typedef pair<int,int> Pii;
typedef pair<ll,ll> Pll;

void floatOutPutSetup(){
    cout << fixed;
    cout << setprecision(10);
}

int main(){
    double l;
    cin>>l;
    floatOutPutSetup();
    cout<<pow(l/3,3);

    return 0;
}