import java.util.Scanner;
public class Main
{
 	public static void main(String[] args)
    {
     	Scanner sc = new Scanner(System.in);
      	double sep = sc.nextDouble();
      	double num = sep / 3;
      	System.out.println(num * num * num);
    }
  
} import java.util.Scanner; Scanner java.util public class Main
{
 	public static void main(String[] args)
    {
     	Scanner sc = new Scanner(System.in);
      	double sep = sc.nextDouble();
      	double num = sep / 3;
      	System.out.println(num * num * num);
    }
  
} Main public static void main(String[] args)
    {
     	Scanner sc = new Scanner(System.in);
      	double sep = sc.nextDouble();
      	double num = sep / 3;
      	System.out.println(num * num * num);
    } main {
     	Scanner sc = new Scanner(System.in);
      	double sep = sc.nextDouble();
      	double num = sep / 3;
      	System.out.println(num * num * num);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) double sep = sc.nextDouble(); sep sc.nextDouble() sc.nextDouble sc double num = sep / 3; num sep / 3 sep 3 System.out.println(num * num * num) System.out.println System.out System System.out num * num * num num * num * num num num num String[] args args public class Main
{
 	public static void main(String[] args)
    {
     	Scanner sc = new Scanner(System.in);
      	double sep = sc.nextDouble();
      	double num = sep / 3;
      	System.out.println(num * num * num);
    }
  
} public class Main
{
 	public static void main(String[] args)
    {
     	Scanner sc = new Scanner(System.in);
      	double sep = sc.nextDouble();
      	double num = sep / 3;
      	System.out.println(num * num * num);
    }
  
} Main
import java.util.Scanner;
public class Main
{
 	public static void main(String[] args)
    {
     	Scanner sc = new Scanner(System.in);
      	double sep = sc.nextDouble();
      	double num = sep / 3;
      	System.out.println(num * num * num);
    }
  
}