import java.util.*;
import java.io.*;
public class Main {
	public static void main(String[] args) throws IOException {
    	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      	double n = Integer.parseInt(br.readLine());
      	System.out.println((n/3)*(n/3)*(n/3));
    }
} import java.util.*; util.* java import java.io.*; io.* java public class Main {
	public static void main(String[] args) throws IOException {
    	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      	double n = Integer.parseInt(br.readLine());
      	System.out.println((n/3)*(n/3)*(n/3));
    }
} Main public static void main(String[] args) throws IOException {
    	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      	double n = Integer.parseInt(br.readLine());
      	System.out.println((n/3)*(n/3)*(n/3));
    } main {
    	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      	double n = Integer.parseInt(br.readLine());
      	System.out.println((n/3)*(n/3)*(n/3));
    } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) double n = Integer.parseInt(br.readLine()); n Integer.parseInt(br.readLine()) Integer.parseInt Integer br.readLine() br.readLine br System.out.println((n/3)*(n/3)*(n/3)) System.out.println System.out System System.out (n/3)*(n/3)*(n/3) (n/3)*(n/3)*(n/3) (n/3) n 3 (n/3) n 3 (n/3) n 3 String[] args args public class Main {
	public static void main(String[] args) throws IOException {
    	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      	double n = Integer.parseInt(br.readLine());
      	System.out.println((n/3)*(n/3)*(n/3));
    }
} public class Main {
	public static void main(String[] args) throws IOException {
    	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      	double n = Integer.parseInt(br.readLine());
      	System.out.println((n/3)*(n/3)*(n/3));
    }
} Main
import java.util.*;
import java.io.*;
public class Main {
	public static void main(String[] args) throws IOException {
    	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      	double n = Integer.parseInt(br.readLine());
      	System.out.println((n/3)*(n/3)*(n/3));
    }
}