import java.util.Scanner;

public class Main {

	private static Scanner scan = new Scanner(System.in);

	public static void main(String[] args) {

		int l = scan.nextInt();
		double a = l/3.0;
		double b = (l-a)/2.0;
		double c = l-a-b;

		System.out.println(a*b*c);

	}
} import java.util.Scanner; Scanner java.util public class Main {

	private static Scanner scan = new Scanner(System.in);

	public static void main(String[] args) {

		int l = scan.nextInt();
		double a = l/3.0;
		double b = (l-a)/2.0;
		double c = l-a-b;

		System.out.println(a*b*c);

	}
} Main private static Scanner scan = new Scanner(System.in); scan new Scanner(System.in) public static void main(String[] args) {

		int l = scan.nextInt();
		double a = l/3.0;
		double b = (l-a)/2.0;
		double c = l-a-b;

		System.out.println(a*b*c);

	} main {

		int l = scan.nextInt();
		double a = l/3.0;
		double b = (l-a)/2.0;
		double c = l-a-b;

		System.out.println(a*b*c);

	} int l = scan.nextInt(); l scan.nextInt() scan.nextInt scan double a = l/3.0; a l/3.0 l 3.0 double b = (l-a)/2.0; b (l-a)/2.0 (l-a) l a 2.0 double c = l-a-b; c l-a-b l-a-b l a b System.out.println(a*b*c) System.out.println System.out System System.out a*b*c a*b*c a b c String[] args args public class Main {

	private static Scanner scan = new Scanner(System.in);

	public static void main(String[] args) {

		int l = scan.nextInt();
		double a = l/3.0;
		double b = (l-a)/2.0;
		double c = l-a-b;

		System.out.println(a*b*c);

	}
} public class Main {

	private static Scanner scan = new Scanner(System.in);

	public static void main(String[] args) {

		int l = scan.nextInt();
		double a = l/3.0;
		double b = (l-a)/2.0;
		double c = l-a-b;

		System.out.println(a*b*c);

	}
} Main
import java.util.Scanner;

public class Main {

	private static Scanner scan = new Scanner(System.in);

	public static void main(String[] args) {

		int l = scan.nextInt();
		double a = l/3.0;
		double b = (l-a)/2.0;
		double c = l-a-b;

		System.out.println(a*b*c);

	}
}