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)

/*-------------------------------------------------
|  __                                       __    |
| |  |--.-----.---.-.----.----.-----.-----.|  |_  |
| |  _  |  -__|  _  |  __|  __|  -__|  _  ||   _| |
| |_____|_____|___._|____|____|_____|   __||____| |
|                                   |__|          |
-------------------------------------------------*/
#include<algorithm>
#include<bitset>
#include<cmath>
#include<complex>
#include<deque>
#include<functional>
#include<iomanip>
#include<iostream>
#include<iterator>
#include<map>
#include<numeric>
#include<queue>
#include<set>
#include<stack>
#include<string>
#include<utility>
#include<vector>
typedef long long lint; using namespace std;
#define rep(counter, limit) for (int counter = 0; counter < (limit); counter++)
#define INF 1000000000000
#define MOD 10000007
int gcd(int a, int b) { if (a % b == 0) { return(b); } else { return(gcd(b, a % b)); } }
int lcm(int a, int b) { return a * b / gcd(a, b); }
bool primenum(int a) { if (a == 1) { return false; }if (a == 2) { return true; }if (a % 2 == 0) { return false; }for (int i = 3; i < sqrt(a) + 1; i += 2) { if (a != i) { if (a % i == 0) { return false; } } }return true; }
struct setupios{setupios(){cin.tie(0);ios::sync_with_stdio(0); cout<<fixed<<setprecision(20);};}setupios;
int main() {

  lint l;cin>>l;l/=3;
  cout<<pow(l,3)<<endl;

}