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