import java.util.Scanner;
public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int l = sc.nextInt();
        double k = (double)(l / 3.0);
        double tai = k * k * k;
        System.out.println(tai);
        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();
        double k = (double)(l / 3.0);
        double tai = k * k * k;
        System.out.println(tai);
        sc.close();
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int l = sc.nextInt();
        double k = (double)(l / 3.0);
        double tai = k * k * k;
        System.out.println(tai);
        sc.close();
    } main {
        Scanner sc = new Scanner(System.in);
        int l = sc.nextInt();
        double k = (double)(l / 3.0);
        double tai = k * k * k;
        System.out.println(tai);
        sc.close();
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int l = sc.nextInt(); l sc.nextInt() sc.nextInt sc double k = (double)(l / 3.0); k (double)(l / 3.0) l 3.0 double tai = k * k * k; tai k * k * k k * k * k k k k System.out.println(tai) System.out.println System.out System System.out tai 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();
        double k = (double)(l / 3.0);
        double tai = k * k * k;
        System.out.println(tai);
        sc.close();
    }
} public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int l = sc.nextInt();
        double k = (double)(l / 3.0);
        double tai = k * k * k;
        System.out.println(tai);
        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();
        double k = (double)(l / 3.0);
        double tai = k * k * k;
        System.out.println(tai);
        sc.close();
    }
}