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 <iostream>
#include <string>
#include <cstdlib>
#include <vector>
#include <array>
#include <map>
#include <set>
#include <algorithm>
#include <queue>
#include <stack>
#define _USE_MATH_DEFINES
#include <cmath>
#include <climits>
#include <cstdio>
#include <iomanip>
#include <utility>
#include <unordered_map>

using namespace std;
typedef long long int ll;

#define SP(x) setprecision((int)x)
#define SW(x) setw(x)    // 桁数指定
#define SF(c) setfill(c) // 埋め文字指定('0')
#define ALL(v) v.begin(), v.end()

int main(int argc, char const *argv[])
{
    long double l;
    cin >> l;
    cout << SP(10) << (l / 3.0) * (l / 3.0) * (l / 3.0) << endl;
}