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 <bits/stdc++.h>
 
using namespace std;
 
#define sf(n) scanf("%d", &n)
#define pd(n) printf("%.10lf", n)
#define pf(n) printf("%d", n)
#define p() printf("\n")
#define ps() printf(" ")
#define ll long long
#define ull unsigned long long
#define MAX 1e9
const int mod = 1000 * 1000 * 1000 + 7;
#define ex 1e18
#define dbl 2e09
#define qu(q) queue<int> q
#define pqu(q) priority_queue<int> q
#define len(s) s.length()
#define sz(x) int(x.size())
#define pb(x) push_back(x)
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define F first
#define S second
#define clr(x) x.clear()
#define LOG(x) std::cout << x << std::endl;
 
const int INF = 0x3f3f3f3f;
const ll LL_INF = 0x3f3f3f3f3f3f3f3f;
const double PI = 3.14159265359;
 
int dx[6] = {-1,-1,0,0,1,1};
int dy[6] = {-1,0,-1,1,0,1};

const int N = 3e5+5;

bool ispalidrome(string s){
    for(int i=0;i<s.size()/2;++i){
        if(s[i]!=s[sz(s)-1-i])
            return false;
    }
    return true;
}


int main(){
    int l;
    cin>>l;
    double ans = l/3.0;
    pd(ans*ans*ans);
    p();
    return 0;
}