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++ (GCC 5.4.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
/*#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>*/
#define ll long long
#define ld long double
#define vll vector <ll>
#define vvll vector <vll>
#define pll pair <ll, ll>
#define vpll vector <pll>
 
#define rep(i, a, b) for(ll i = a; i < b; i++)
#define per(i, a, b) for(ll i = a - 1; i >= b; --i)
 
#define endl "\n"
#define pb push_back
#define pf push_front
 
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
 
#define sorta(v) sort(all(v))
#define sortd(v) sort(rall(v))
#define vld vector<ld>
 
#define debug if (1)
#define log(val) debug {clog << "\n" << #val << ": " << val << "\n";}
 
#define ios ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
 
#define mod (ll)(1e9 + 7)
 
using namespace std;

const ll N = 2e5 + 5;

ll mas[N];

void solve() {
    ld n;
    cin >> n;
    
    n /= 3;
    
    n = pow(n, 3.0);
    
    cout << setprecision(6) << fixed << n;
}

int main() {
    //ios
    //mt19937 rng(chrono::steady_clock::now().time_since_epoch().count())
    
    ll tests = 1;
    //cin >> tests;
    while (tests--) {
        solve();
    }
 
    return 0;
}