

import java.io.*;
import java.util.*;


public class Main
{

	public static void main(String[] args)throws Exception
	{
		Scanner sc = new Scanner(System.in);
		
		Double a = sc.nextDouble();

		Double f= Math.pow(a/3, 3);
		System.out.printf("%.12f",f);
	}

} import java.io.*; io.* java import java.util.*; util.* java public class Main
{

	public static void main(String[] args)throws Exception
	{
		Scanner sc = new Scanner(System.in);
		
		Double a = sc.nextDouble();

		Double f= Math.pow(a/3, 3);
		System.out.printf("%.12f",f);
	}

} Main public static void main(String[] args)throws Exception
	{
		Scanner sc = new Scanner(System.in);
		
		Double a = sc.nextDouble();

		Double f= Math.pow(a/3, 3);
		System.out.printf("%.12f",f);
	} main {
		Scanner sc = new Scanner(System.in);
		
		Double a = sc.nextDouble();

		Double f= Math.pow(a/3, 3);
		System.out.printf("%.12f",f);
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) Double a = sc.nextDouble(); a sc.nextDouble() sc.nextDouble sc Double f= Math.pow(a/3, 3); f Math.pow(a/3, 3) Math.pow Math a/3 a 3 3 System.out.printf("%.12f",f) System.out.printf System.out System System.out "%.12f" f String[] args args public class Main
{

	public static void main(String[] args)throws Exception
	{
		Scanner sc = new Scanner(System.in);
		
		Double a = sc.nextDouble();

		Double f= Math.pow(a/3, 3);
		System.out.printf("%.12f",f);
	}

} public class Main
{

	public static void main(String[] args)throws Exception
	{
		Scanner sc = new Scanner(System.in);
		
		Double a = sc.nextDouble();

		Double f= Math.pow(a/3, 3);
		System.out.printf("%.12f",f);
	}

} Main


import java.io.*;
import java.util.*;


public class Main
{

	public static void main(String[] args)throws Exception
	{
		Scanner sc = new Scanner(System.in);
		
		Double a = sc.nextDouble();

		Double f= Math.pow(a/3, 3);
		System.out.printf("%.12f",f);
	}

}
