import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int l = sc.nextInt();
        System.out.println((double)4 * l * l * l / 108);
        sc.close();
    }
} 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();
        System.out.println((double)4 * l * l * l / 108);
        sc.close();
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int l = sc.nextInt();
        System.out.println((double)4 * l * l * l / 108);
        sc.close();
    } main {
        Scanner sc = new Scanner(System.in);
        int l = sc.nextInt();
        System.out.println((double)4 * l * l * l / 108);
        sc.close();
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int l = sc.nextInt(); l sc.nextInt() sc.nextInt sc System.out.println((double)4 * l * l * l / 108) System.out.println System.out System System.out (double)4 * l * l * l / 108 (double)4 * l * l * l l (double)4 * l * l * l (double)4 l l l 108 sc.close() sc.close sc String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int l = sc.nextInt();
        System.out.println((double)4 * l * l * l / 108);
        sc.close();
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int l = sc.nextInt();
        System.out.println((double)4 * l * l * l / 108);
        sc.close();
    }
} Main
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int l = sc.nextInt();
        System.out.println((double)4 * l * l * l / 108);
        sc.close();
    }
}