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 rep(i,n) for (int i=0; i<(n); ++i)
#define rrep(i, n) for (int i = 1; i < (n); ++i)
using namespace std;
using ll = long long;
using P = pair<int, int>;

// ll A, B, C;
// scanf("%ld %ld %ld", &A, &B, &C);
// printf("%ld %ld %ld", A, B, C);

int main()
{
    float L;
    float l, ans;
    cin >> L;
    l = L/3;
    // cout << "l: " << l << endl;
    ans=l*l*l;
    cout << ans << endl;

    return 0;
}