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 <stdio.h>


int main()
{
    double l,a,b,c;
    scanf("%lf",&l);
    a=l/3;
   // printf("%f   \n",a);
    double vmax=a*a*a;
    for(;a<l;a++){
        for(b=l/3;b<l;b++){
            for(c=l/3;c<l;c++)
                if(a+b+c==l && a*b*c>vmax)
                vmax=a*b*c;
        }
    }
    printf("%.12f",vmax);
    return 0;
}