import java.io.IOException;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws IOException {
	    Scanner sc = new Scanner(System.in);
	    double L = sc.nextInt();
	    sc.close();

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

	}

} import java.io.IOException; IOException java.io import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) throws IOException {
	    Scanner sc = new Scanner(System.in);
	    double L = sc.nextInt();
	    sc.close();

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

	}

} Main public static void main(String[] args) throws IOException {
	    Scanner sc = new Scanner(System.in);
	    double L = sc.nextInt();
	    sc.close();

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

	} main {
	    Scanner sc = new Scanner(System.in);
	    double L = sc.nextInt();
	    sc.close();

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

	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) double L = sc.nextInt(); L sc.nextInt() sc.nextInt sc sc.close() sc.close sc System.out.println(Math.pow(L/3,3)) System.out.println System.out System System.out Math.pow(L/3,3) Math.pow Math L/3 L 3 3 String[] args args public class Main {
	public static void main(String[] args) throws IOException {
	    Scanner sc = new Scanner(System.in);
	    double L = sc.nextInt();
	    sc.close();

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

	}

} public class Main {
	public static void main(String[] args) throws IOException {
	    Scanner sc = new Scanner(System.in);
	    double L = sc.nextInt();
	    sc.close();

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

	}

} Main
import java.io.IOException;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws IOException {
	    Scanner sc = new Scanner(System.in);
	    double L = sc.nextInt();
	    sc.close();

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

	}

}
