import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        String l1 = scan.nextLine();
        scan.close();

        int L = Integer.valueOf(l1);
        double side = L / 3.0;
        System.out.println(String.format("%.12f", side * side * side));
	}
} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        String l1 = scan.nextLine();
        scan.close();

        int L = Integer.valueOf(l1);
        double side = L / 3.0;
        System.out.println(String.format("%.12f", side * side * side));
	}
} Main public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        String l1 = scan.nextLine();
        scan.close();

        int L = Integer.valueOf(l1);
        double side = L / 3.0;
        System.out.println(String.format("%.12f", side * side * side));
	} main {
        Scanner scan = new Scanner(System.in);
        String l1 = scan.nextLine();
        scan.close();

        int L = Integer.valueOf(l1);
        double side = L / 3.0;
        System.out.println(String.format("%.12f", side * side * side));
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) String l1 = scan.nextLine(); l1 scan.nextLine() scan.nextLine scan scan.close() scan.close scan int L = Integer.valueOf(l1); L Integer.valueOf(l1) Integer.valueOf Integer l1 double side = L / 3.0; side L / 3.0 L 3.0 System.out.println(String.format("%.12f", side * side * side)) System.out.println System.out System System.out String.format("%.12f", side * side * side) String.format String "%.12f" side * side * side side * side * side side side side String[] args args public class Main {

	public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        String l1 = scan.nextLine();
        scan.close();

        int L = Integer.valueOf(l1);
        double side = L / 3.0;
        System.out.println(String.format("%.12f", side * side * side));
	}
} public class Main {

	public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        String l1 = scan.nextLine();
        scan.close();

        int L = Integer.valueOf(l1);
        double side = L / 3.0;
        System.out.println(String.format("%.12f", side * side * side));
	}
} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        String l1 = scan.nextLine();
        scan.close();

        int L = Integer.valueOf(l1);
        double side = L / 3.0;
        System.out.println(String.format("%.12f", side * side * side));
	}
}