import java.util.*;
public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int l = sc.nextInt();
    double max=0;
    
    double z=(double)l/3.0;
    System.out.println(z*z*z);
    
  }
} import java.util.*; util.* java public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int l = sc.nextInt();
    double max=0;
    
    double z=(double)l/3.0;
    System.out.println(z*z*z);
    
  }
} Main public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int l = sc.nextInt();
    double max=0;
    
    double z=(double)l/3.0;
    System.out.println(z*z*z);
    
  } main {
    Scanner sc = new Scanner(System.in);
    int l = sc.nextInt();
    double max=0;
    
    double z=(double)l/3.0;
    System.out.println(z*z*z);
    
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int l = sc.nextInt(); l sc.nextInt() sc.nextInt sc double max=0; max 0 double z=(double)l/3.0; z (double)l/3.0 (double)l 3.0 System.out.println(z*z*z) System.out.println System.out System System.out z*z*z z*z*z z z z String[] args args public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int l = sc.nextInt();
    double max=0;
    
    double z=(double)l/3.0;
    System.out.println(z*z*z);
    
  }
} public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int l = sc.nextInt();
    double max=0;
    
    double z=(double)l/3.0;
    System.out.println(z*z*z);
    
  }
} Main
import java.util.*;
public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int l = sc.nextInt();
    double max=0;
    
    double z=(double)l/3.0;
    System.out.println(z*z*z);
    
  }
}