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
import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        double L = sc.nextDouble();

        System.out.println(Math.pow(L / 3, 3));
    }
}
