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);

		// 入力値の取得
		int L = sc.nextInt();
		
		// 結果の出力
		System.out.println(Math.pow(L, 3) / 27);

		sc.close();
	}
}