Problem: 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}.

Examples

Input

3


Output

1.000000000000


Input

999


Output

36926037.000000000000

Solution (in JAVA):

Solution:
import java.util.*;

public class Main{
public static void main(String[]args){
    double a = 0.0;
    Scanner sc = new Scanner(System.in);
    a = sc.nextInt();
    double count =0.0;
    count=a*a*a/27.0;
    System.out.println(count);
}

}