import java.util.*;
public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
  	int l=sc.nextInt();
  	double a=((double)l)/3;
  	System.out.print(Math.pow(a,3));
  }
} 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 a=((double)l)/3;
  	System.out.print(Math.pow(a,3));
  }
} Main public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
  	int l=sc.nextInt();
  	double a=((double)l)/3;
  	System.out.print(Math.pow(a,3));
  } main {
    Scanner sc = new Scanner(System.in);
  	int l=sc.nextInt();
  	double a=((double)l)/3;
  	System.out.print(Math.pow(a,3));
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int l=sc.nextInt(); l sc.nextInt() sc.nextInt sc double a=((double)l)/3; a ((double)l)/3 ((double)l) 3 System.out.print(Math.pow(a,3)) System.out.print System.out System System.out Math.pow(a,3) Math.pow Math a 3 String[] args args public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
  	int l=sc.nextInt();
  	double a=((double)l)/3;
  	System.out.print(Math.pow(a,3));
  }
} public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
  	int l=sc.nextInt();
  	double a=((double)l)/3;
  	System.out.print(Math.pow(a,3));
  }
} Main
import java.util.*;
public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
  	int l=sc.nextInt();
  	double a=((double)l)/3;
  	System.out.print(Math.pow(a,3));
  }
}