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.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double l = sc.nextLong();
		l = Math.pow(l, 3);
		l /= 27;
		System.out.println(l);
	}

}