//referred professors code
import java.util.Scanner;
 
public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int l = sc.nextInt();
		double a = l/3.0;
		System.out.printf("%.6f\n", a*a*a);
    }
} import java.util.Scanner; Scanner java.util public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int l = sc.nextInt();
		double a = l/3.0;
		System.out.printf("%.6f\n", a*a*a);
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int l = sc.nextInt();
		double a = l/3.0;
		System.out.printf("%.6f\n", a*a*a);
    } main {
        Scanner sc = new Scanner(System.in);
        int l = sc.nextInt();
		double a = l/3.0;
		System.out.printf("%.6f\n", a*a*a);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int l = sc.nextInt(); l sc.nextInt() sc.nextInt sc double a = l/3.0; a l/3.0 l 3.0 System.out.printf("%.6f\n", a*a*a) System.out.printf System.out System System.out "%.6f\n" a*a*a a*a*a a a a String[] args args public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int l = sc.nextInt();
		double a = l/3.0;
		System.out.printf("%.6f\n", a*a*a);
    }
} public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int l = sc.nextInt();
		double a = l/3.0;
		System.out.printf("%.6f\n", a*a*a);
    }
} Main
//referred professors code
import java.util.Scanner;
 
public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int l = sc.nextInt();
		double a = l/3.0;
		System.out.printf("%.6f\n", a*a*a);
    }
}