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: Wrong Answer)

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       '`  ` |-|   `` '
             |-|
             |-|O                    2020 @ CodeForces, CodeChef, CCC & More!
             |-(\,__
          ...|-|\--,\_....
      ,;;;;;;;;;;;;;;;;;;;;;;;;,.
~~,;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;,~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;,  ______   ---------   _____     ------
 */


//Optimisation
#pragma GCC optimize("O3")
//(UNCOMMENT WHEN HAVING LOTS OF RECURSIONS)\
#pragma comment(linker, "/stack:200000000")
//(UNCOMMENT WHEN NEEDED)\
#pragma GCC optimize("Ofast,unroll-loops,no-stack-protector,fast-math")\
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")


//Imports
#include <algorithm>
#include <cmath>
#include <cstdlib>
#include <cstdio>
#include <iostream>
#include <iomanip>
#include <map>
#include <string>
#include <stack>
#include <set>
#include <sstream>
#include <queue>
#include <vector>

using namespace std;

//Macros
#define el '\n'
#define elc << el;
#define debug(x) cout << ">>" << x << el;
#define rep(i, c) for(int i = 0; i <(c); ++i)
#define fora(i, s, c) for(int i = (s); i < (c); ++i)
#define forr(i, s, c) for(int i = (s); i > (c); --i)
#define pb push_back
#define eb emplace_back
#define ff first;
#define ss second;
#define mp make_pair;
#define all(p) p.begin(),p.end()
#define max(x,y) (x>y)?x:y
#define min(x,y) (x<y)?x:y
#define mid(s,e) (s+(e-s)/2)
#define absv(a) (a<0)?(-1*a):a
#define negv(a) (a>0)?(-1*a):a
#define arrset(a,b,v) rep(i, b) a[i]=v //Sets array to a value, where a is the array, b is the count, and v is the value

//Typedefs
typedef long long ll;
typedef vector<int> vi;
typedef vector<vector<int> > vvi;
typedef pair<ll,ll> pll;
typedef pair<int,int> pii;

//Random Stuff
#define Pi 3.141592653589793
#define space << ' ' <<
const ll mod = 1000000007;

//Functions
inline int twop(int n) { return 1 << n; }
template<class T> T gcd(T a,T b){if(b == 0)return a;return gcd(b,a%b);}
template<class T> T lcm(T a, T b ){return (a*b)/gcd(a,b);}

//Testcase start
#define tcs() int testcases; cin >> testcases; while(testcases--)

int main() {
	//Fast io for cin / cout
	ios_base::sync_with_stdio(false);
	cin.tie(0); //Comment out if there is large exchange of cin / cout
	cout.tie(0);

	//USE FOR TESTCASE PROBLEMS
	long double sum;
	cin >> sum;

	long double s1 = sum/3;

	cout << s1*s1*s1 elc;

	return 0;
}