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>
using namespace std;
#define ll long long
#define space " "
#define MOD (long long) 1000000007
#define trace(...) __f(#__VA_ARGS__, __VA_ARGS__)
template <typename T> void __f(const char* variable_name, T&& value){cout << variable_name << ": " << value << endl;}
template <typename T1, typename... T2> void __f(const char* names, T1&& arg1, T2&&... args){const char* comma = strchr(names + 1, ',');cout.write(names, comma - names) << ": " << arg1 << " |";__f(comma + 1, args...);}

const ll N = 5e5 + 5;
ll *v;
ll n, m;

void solve(){
    cin >> n;
    double x = n / 3;
    double ans = x * x * x;
    cout << setprecision(6) << ans << endl;
}

int main(){
    ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
    ll t = 1;
    // cout << "\n\nBLAH BLAH BLAH\n\n";
    // cin >> t;
    while(t--){
        solve();
    }
    return 0;
}