import java.util.Scanner;

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

		System.out.println(String.format("%.12f", Math.pow((double)L, 3.0) / 27.0));
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int L = scanner.nextInt();

		System.out.println(String.format("%.12f", Math.pow((double)L, 3.0) / 27.0));
	}
} Main public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int L = scanner.nextInt();

		System.out.println(String.format("%.12f", Math.pow((double)L, 3.0) / 27.0));
	} main {
		Scanner scanner = new Scanner(System.in);
		int L = scanner.nextInt();

		System.out.println(String.format("%.12f", Math.pow((double)L, 3.0) / 27.0));
	} Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int L = scanner.nextInt(); L scanner.nextInt() scanner.nextInt scanner System.out.println(String.format("%.12f", Math.pow((double)L, 3.0) / 27.0)) System.out.println System.out System System.out String.format("%.12f", Math.pow((double)L, 3.0) / 27.0) String.format String "%.12f" Math.pow((double)L, 3.0) / 27.0 Math.pow((double)L, 3.0) Math.pow Math (double)L 3.0 27.0 String[] args args public class Main {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int L = scanner.nextInt();

		System.out.println(String.format("%.12f", Math.pow((double)L, 3.0) / 27.0));
	}
} public class Main {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int L = scanner.nextInt();

		System.out.println(String.format("%.12f", Math.pow((double)L, 3.0) / 27.0));
	}
} Main
import java.util.Scanner;

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

		System.out.println(String.format("%.12f", Math.pow((double)L, 3.0) / 27.0));
	}
}