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: Wrong Answer)

#include <stdio.h>
 
main( )
{
//  int	x;
  double x,i,j,y,max;
//  float i,j,x,y,max;
  
  max = 0;
  
  scanf("%lf",&x);
  
  for( i=0.1; i<x; i+=0.1 ){
    for( j=0.1; j<x-i-0.1; j+=0.1 ){
      y = i * j * (x-i-j);
 //  printf("%.12f\n",max);
//  printf("%lf,",i);
//  printf("%lf,",j);
//  printf("%lf\n",(x-i-j));  
 
      if( max < y ){
        
        max = y;
      }
    }
  }
  printf("%lf\n",max);
//  printf("%lf,",i);
//  printf("%lf,",j);
//  printf("%lf\n",(x-i-j));  
}