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>
#define rep(i, n) for (int i=0;i<(n);i++)
using namespace std;
typedef long long ll;

int main(void){
    int l;
    cin>>l;
    double ans=0.0;
    double a=((double)l)/3;
    ans=a*a*a;
    /*for(int i=1;i<=l;i++){
        for(int j=1;j<=l;j++){
            int k=l-i-j;
            if(k<=0) continue;
            double t=(double)i*(double)j*(double)k;
            ans=max(ans, t);
        }
    }*/
    printf("%.10f\n", ans);
    return 0;
}