import java.util.Scanner;

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

class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
	int L =  sc.nextInt();
	double x = (double)L/3;
	double V = x*x*x;
    System.out.println(V) ;
  }
}