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 LL long long
    # define int long long
    #define gok ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    # define mo 998244353
    # define pi acos(-1)
    //vector<pair<int,int>> v;
    //int x0=INT_MAX,y0=INT_MAX;
    /*int crossprod(pair<int,int> a,pair<int,int> b,pair<int,int> c)
    {
        int x1 = a.first-b.first;
        int x2 = a.first-c.first;
        int y1 = a.second-b.second;
        int y2 = a.second-c.second;
        return x1*y2 - y1*x2;
    }
    int direction(pair<int,int> a,pair<int,int> b,pair<int,int> c) {
       int val = (b.y-a.y)*(c.x-b.x)-(b.x-a.x)*(c.y-b.y);
       if (val == 0)
          return 0;     //colinear
       else if(val < 0)
          return 2;    //anti-clockwise direction
          return 1;    //clockwise direction
    }*/
   vector<int> v[102];
    signed main(){
        gok

     int n;
     cin>>n;
     double ss = n/3.0;

  cout<<fixed<<setprecision(10)<<(ss*ss*ss);





        return 0;
    }