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