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) {
		Scanner sc = new Scanner(System.in);
		
		int L = sc.nextInt();
		//a=b=c=L/3のとき最大なので、その時の体積はLの3乗/27となる
		System.out.println((double)L*L*L/27);
	}		
}