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)

/***
 **   A S M Atikur Rahman
 **   Update: 17-12-2019
***/

//#include <bits/stdc++.h>
#include<iostream>
#include<stdio.h>
#include<stdlib.h>
#include<math.h>
#include<cstring>
#include<time.h>
#include<limits.h>
#include<vector>
#include<string>
#include<stack>
#include<queue>
#include<map>
#include<unordered_map>
#include<set>
#include<unordered_set>
#include<utility>
#include<iterator>
#include<algorithm>
#include<cassert>
#include<iomanip> ///setprecision


#define IOS ios_base::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);
#define sci(x) scanf("%d%*c", &(x))
#define scll(x) scanf("%lld%*c", &(x))
#define scd(x) scanf("%lf%*c", &(x))
#define scstr(x) scanf("%s", x)
#define pfi(x) printf("%d", (x))
#define pfll(x) printf("%lld", (x))
#define pfd(x) printf("%f", (x))
#define pfstr(x) printf("%s", (x))
#define ps printf(" ")
#define pn printf("\n")
#define pfdot printf("..")

#define For(a,n) for(int i=(a); i<(n); i++)
#define rFor(n,a) for(int i=n-1; i>=0; i--)
#define trav(a,x) for (auto& a : x)
#define Mset(ara, val) memset(ara, val, sizeof(ara))

#define mkp make_pair
#define pb push_back
#define ff first
#define ss second
#define lb lower_bound
#define ub upper_bound

#define pi  (2*acos(0))


using namespace std;

using ll=long long;
using pii= pair<int,int>;
using pll= pair<long long, long long>;
using pcc= pair<char, char>;
using pdd= pair<double, double>;

#define V(a) vector<a>
using vi= vector<int>;
using vs= vector<string>;
using vll= vector<ll>;
using vpii= vector<pii>;
using vc= vector<char>;
using vd= vector<double>;

ll POW(ll a,ll b){if(b==0)return 1;ll x=POW(a,b/2);x=(x*x);if(b&1)x=(x*a);return x;}




int main( int argc, char *argv[] )
{
//    freopen("input.txt", "r", stdin);
//    freopen("output.txt", "w", stout);
    double l,ans;
    scd(l);
    l=l/3;
    ans=pow(l,3);
    pfd(ans),pn;





    return 0;
}