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