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>
#define pb push_back
#define mp make_pair
#define lli long long int
#define llu long long unsigned int
#define IOS ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define FOR(i,s,e) for(i=s; i<e; i++)
#define F first
#define S second
#define plli pair<lli,lli>
#define pqlli priority_queue<lli>
#define test(t) cin>>t; while(t--)
#define MX 5003
using namespace std;

int main() 
{
	IOS;
	int l;
	cin>>l;
	double ll = ((double)l)/3;
	double temp = (ll*ll*ll);
	cout<<fixed<<setprecision(12)<<temp<<endl;
}