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;
typedef long long int ll;
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#define  boost ios_base::sync_with_stdio(false);cin.tie(NULL);
#define ull unsigned long long
#define deb(x) cout<<#x<<" "<<x<<endl;
#define deb2(x,y) cout<<#x<<" "<<x<<" "<<#y<<" "<<y<<endl;
#define deb2l(x,y,i) cout<<#x<<i<<" "<<x<<" "<<#y<<i<<" "<<y<<endl;

#define fr(i,l,r) for(ll i=l;i<r;i++)
#define mems(a,x) memset(a,x,sizeof(a))
#define mod 1000000007
#define ff first
#define ss second
#define pb(x) push_back(x)
#define vll vector<ll>
#define pbp(x,y) push_back(make_pair(x,y))
#define  mat vector<vector<ll>>
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

bool isp(string &s,ll i,ll j){
    ll f=1;
    while(i<=j && f){
        if(s[i]!=s[j])
        f=0;
        i++,j--;
    }
    return f;
}
void solve(){
    long double n;
    cin>>n;
    long double k=3.0*3.0*3.0;
    n=n*n*n;
    cout<<fixed;
    cout<<setprecision(12)<<n/k;

  
  }
int main(){
    ll t=1;
   // cin>>t;
    while(t--){
        solve();
        cout<<endl;
    }
    return 0;
}