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 <bits/stdc++.h>

#define FIO ios_base::sync_with_stdio(0); cin.tie(0);
#define T() int tt; cin >> tt; rep1(qq,1,tt)
#define rep(i,start,lim) for(int i=start;i<lim;i++)
#define rep1(i,start,lim) for(int i=start; i<=lim; ++i)
#define repd(i,start,lim) for(int i=start;i>=lim;i--)
#define mp make_pair
#define pb push_back
#define ff first
#define ss second
#define br cout<<"\n"
#define MOD (998244353LL)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define eps (1e-6)
#define what_is(x) cerr << #x << " is " << x << "\n";
#define int long long int
#define infll 9e18
#define inf 1e12

#define lnode (2 * node + 1)
#define rnode (2 * node + 2)

using namespace std;

typedef pair<int, int> pii;

const int N = 2e5 + 5;

int l;

int32_t main()
{

	FIO
	cout << fixed << setprecision(6);
	//freopen("input.txt", "r", stdin);
	//freopen("output.txt", "w", stdout);
	
	double res = 0.0;
	cin >> l;
	for(double i = 0.1; i < l; i += 0.1){
	  for(double j = 0.1; j < l; j += 0.1){
	    double k = l - (i + j);
	    if(k <= 0.0) continue;
	    res = max(res, 1.0 * i * j * k);
    }
  }
	cout << res;
	return 0;
}