import java.util.Scanner;

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

public class Main {
	
	public static void main(String[] args)
	{
		Scanner s=new Scanner(System.in);
		
		double l=s.nextDouble();
		
		double side=l/3;
		
		System.out.println(side*side*side);
		
	}
	
}