import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		double L = scan.nextDouble();

		System.out.println((L/3)*(L/3)*(L/3));

	}

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

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		double L = scan.nextDouble();

		System.out.println((L/3)*(L/3)*(L/3));

	}

} Main public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		double L = scan.nextDouble();

		System.out.println((L/3)*(L/3)*(L/3));

	} main {

		Scanner scan = new Scanner(System.in);

		double L = scan.nextDouble();

		System.out.println((L/3)*(L/3)*(L/3));

	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) double L = scan.nextDouble(); L scan.nextDouble() scan.nextDouble scan System.out.println((L/3)*(L/3)*(L/3)) System.out.println System.out System System.out (L/3)*(L/3)*(L/3) (L/3)*(L/3)*(L/3) (L/3) L 3 (L/3) L 3 (L/3) L 3 String[] args args public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		double L = scan.nextDouble();

		System.out.println((L/3)*(L/3)*(L/3));

	}

} public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		double L = scan.nextDouble();

		System.out.println((L/3)*(L/3)*(L/3));

	}

} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		double L = scan.nextDouble();

		System.out.println((L/3)*(L/3)*(L/3));

	}

}