import java.util.Scanner;
import java.text.DecimalFormat;

public class Main
{
    public static void main(String[] args)
    {
        Scanner key = new Scanner(System.in);
        double num = key.nextInt();
        key.close();
        
        System.out.println((num/3)*(num/3)*(num/3));
        
    }
} import java.util.Scanner; Scanner java.util import java.text.DecimalFormat; DecimalFormat java.text public class Main
{
    public static void main(String[] args)
    {
        Scanner key = new Scanner(System.in);
        double num = key.nextInt();
        key.close();
        
        System.out.println((num/3)*(num/3)*(num/3));
        
    }
} Main public static void main(String[] args)
    {
        Scanner key = new Scanner(System.in);
        double num = key.nextInt();
        key.close();
        
        System.out.println((num/3)*(num/3)*(num/3));
        
    } main {
        Scanner key = new Scanner(System.in);
        double num = key.nextInt();
        key.close();
        
        System.out.println((num/3)*(num/3)*(num/3));
        
    } Scanner key = new Scanner(System.in); key new Scanner(System.in) double num = key.nextInt(); num key.nextInt() key.nextInt key key.close() key.close key System.out.println((num/3)*(num/3)*(num/3)) System.out.println System.out System System.out (num/3)*(num/3)*(num/3) (num/3)*(num/3)*(num/3) (num/3) num 3 (num/3) num 3 (num/3) num 3 String[] args args public class Main
{
    public static void main(String[] args)
    {
        Scanner key = new Scanner(System.in);
        double num = key.nextInt();
        key.close();
        
        System.out.println((num/3)*(num/3)*(num/3));
        
    }
} public class Main
{
    public static void main(String[] args)
    {
        Scanner key = new Scanner(System.in);
        double num = key.nextInt();
        key.close();
        
        System.out.println((num/3)*(num/3)*(num/3));
        
    }
} Main
import java.util.Scanner;
import java.text.DecimalFormat;

public class Main
{
    public static void main(String[] args)
    {
        Scanner key = new Scanner(System.in);
        double num = key.nextInt();
        key.close();
        
        System.out.println((num/3)*(num/3)*(num/3));
        
    }
}