import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int l = Integer.parseInt(sc.next());
        double hen = (double) l / 3;
        double ans = hen * hen * hen;
        System.out.println(ans);

        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 = Integer.parseInt(sc.next());
        double hen = (double) l / 3;
        double ans = hen * hen * hen;
        System.out.println(ans);

        sc.close();
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int l = Integer.parseInt(sc.next());
        double hen = (double) l / 3;
        double ans = hen * hen * hen;
        System.out.println(ans);

        sc.close();
    } main {
        Scanner sc = new Scanner(System.in);
        int l = Integer.parseInt(sc.next());
        double hen = (double) l / 3;
        double ans = hen * hen * hen;
        System.out.println(ans);

        sc.close();
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int l = Integer.parseInt(sc.next()); l Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc double hen = (double) l / 3; hen (double) l / 3 (double) l 3 double ans = hen * hen * hen; ans hen * hen * hen hen * hen * hen hen hen hen System.out.println(ans) System.out.println System.out System System.out ans 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 = Integer.parseInt(sc.next());
        double hen = (double) l / 3;
        double ans = hen * hen * hen;
        System.out.println(ans);

        sc.close();
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int l = Integer.parseInt(sc.next());
        double hen = (double) l / 3;
        double ans = hen * hen * hen;
        System.out.println(ans);

        sc.close();
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int l = Integer.parseInt(sc.next());
        double hen = (double) l / 3;
        double ans = hen * hen * hen;
        System.out.println(ans);

        sc.close();
    }
}