import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double a = sc.nextInt();
		double b = a/3.0;
		
		System.out.println(b*b*b);

	}

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

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double a = sc.nextInt();
		double b = a/3.0;
		
		System.out.println(b*b*b);

	}

} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double a = sc.nextInt();
		double b = a/3.0;
		
		System.out.println(b*b*b);

	} main {
		Scanner sc = new Scanner(System.in);
		double a = sc.nextInt();
		double b = a/3.0;
		
		System.out.println(b*b*b);

	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) double a = sc.nextInt(); a sc.nextInt() sc.nextInt sc double b = a/3.0; b a/3.0 a 3.0 System.out.println(b*b*b) System.out.println System.out System System.out b*b*b b*b*b b b b String[] args args public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double a = sc.nextInt();
		double b = a/3.0;
		
		System.out.println(b*b*b);

	}

} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double a = sc.nextInt();
		double b = a/3.0;
		
		System.out.println(b*b*b);

	}

} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double a = sc.nextInt();
		double b = a/3.0;
		
		System.out.println(b*b*b);

	}

}
