import java.util.Scanner;
 
public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
 
		int l = scan.nextInt();
		double a = (double)l / 3.0;
 
		System.out.printf("%.12f" , Math.pow(a, 3));
	}
} 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();
		double a = (double)l / 3.0;
 
		System.out.printf("%.12f" , Math.pow(a, 3));
	}
} Main public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
 
		int l = scan.nextInt();
		double a = (double)l / 3.0;
 
		System.out.printf("%.12f" , Math.pow(a, 3));
	} main {
		Scanner scan = new Scanner(System.in);
 
		int l = scan.nextInt();
		double a = (double)l / 3.0;
 
		System.out.printf("%.12f" , Math.pow(a, 3));
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int l = scan.nextInt(); l scan.nextInt() scan.nextInt scan double a = (double)l / 3.0; a (double)l / 3.0 (double)l 3.0 System.out.printf("%.12f" , Math.pow(a, 3)) System.out.printf System.out System System.out "%.12f" Math.pow(a, 3) Math.pow Math a 3 String[] args args public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
 
		int l = scan.nextInt();
		double a = (double)l / 3.0;
 
		System.out.printf("%.12f" , Math.pow(a, 3));
	}
} public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
 
		int l = scan.nextInt();
		double a = (double)l / 3.0;
 
		System.out.printf("%.12f" , Math.pow(a, 3));
	}
} Main
import java.util.Scanner;
 
public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
 
		int l = scan.nextInt();
		double a = (double)l / 3.0;
 
		System.out.printf("%.12f" , Math.pow(a, 3));
	}
}