import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		int L = scan.nextInt();	
		
		System.out.println((double)L * L * L /27);
	}
} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		int L = scan.nextInt();	
		
		System.out.println((double)L * L * L /27);
	}
} Main public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		int L = scan.nextInt();	
		
		System.out.println((double)L * L * L /27);
	} main {

		Scanner scan = new Scanner(System.in);

		int L = scan.nextInt();	
		
		System.out.println((double)L * L * L /27);
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int L = scan.nextInt(); L scan.nextInt() scan.nextInt scan System.out.println((double)L * L * L /27) System.out.println System.out System System.out (double)L * L * L /27 (double)L * L * L (double)L * L * L (double)L L L 27 String[] args args public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		int L = scan.nextInt();	
		
		System.out.println((double)L * L * L /27);
	}
} public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		int L = scan.nextInt();	
		
		System.out.println((double)L * L * L /27);
	}
} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		int L = scan.nextInt();	
		
		System.out.println((double)L * L * L /27);
	}
}