import java.util.*;
public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		int L = sc.nextInt();
		double x = (double)L/3;
		double y = (double)L/3;
		double z = (double)L/3;
		double P = x*y*z;
		System.out.printf("%.12f",P);
		
	}
	
} import java.util.*; util.* java public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		int L = sc.nextInt();
		double x = (double)L/3;
		double y = (double)L/3;
		double z = (double)L/3;
		double P = x*y*z;
		System.out.printf("%.12f",P);
		
	}
	
} Main public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		int L = sc.nextInt();
		double x = (double)L/3;
		double y = (double)L/3;
		double z = (double)L/3;
		double P = x*y*z;
		System.out.printf("%.12f",P);
		
	} main {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		int L = sc.nextInt();
		double x = (double)L/3;
		double y = (double)L/3;
		double z = (double)L/3;
		double P = x*y*z;
		System.out.printf("%.12f",P);
		
	} 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 y = (double)L/3; y (double)L/3 (double)L 3 double z = (double)L/3; z (double)L/3 (double)L 3 double P = x*y*z; P x*y*z x*y*z x y z System.out.printf("%.12f",P) System.out.printf System.out System System.out "%.12f" P String[] args args public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		int L = sc.nextInt();
		double x = (double)L/3;
		double y = (double)L/3;
		double z = (double)L/3;
		double P = x*y*z;
		System.out.printf("%.12f",P);
		
	}
	
} public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		int L = sc.nextInt();
		double x = (double)L/3;
		double y = (double)L/3;
		double z = (double)L/3;
		double P = x*y*z;
		System.out.printf("%.12f",P);
		
	}
	
} Main
import java.util.*;
public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		int L = sc.nextInt();
		double x = (double)L/3;
		double y = (double)L/3;
		double z = (double)L/3;
		double P = x*y*z;
		System.out.printf("%.12f",P);
		
	}
	
}
