import java.io.IOException;
import java.util.*;

public class Main {

    public static void main(String[] args) throws IOException {
        Scanner in = new Scanner(System.in);
        long l = in.nextLong();

        double c = (double) l / 3;
        double m = c * c * c;
        System.out.println(String.format("%.8f",m));
    }
} import java.io.IOException; IOException java.io import java.util.*; util.* java public class Main {

    public static void main(String[] args) throws IOException {
        Scanner in = new Scanner(System.in);
        long l = in.nextLong();

        double c = (double) l / 3;
        double m = c * c * c;
        System.out.println(String.format("%.8f",m));
    }
} Main public static void main(String[] args) throws IOException {
        Scanner in = new Scanner(System.in);
        long l = in.nextLong();

        double c = (double) l / 3;
        double m = c * c * c;
        System.out.println(String.format("%.8f",m));
    } main {
        Scanner in = new Scanner(System.in);
        long l = in.nextLong();

        double c = (double) l / 3;
        double m = c * c * c;
        System.out.println(String.format("%.8f",m));
    } Scanner in = new Scanner(System.in); in new Scanner(System.in) long l = in.nextLong(); l in.nextLong() in.nextLong in double c = (double) l / 3; c (double) l / 3 (double) l 3 double m = c * c * c; m c * c * c c * c * c c c c System.out.println(String.format("%.8f",m)) System.out.println System.out System System.out String.format("%.8f",m) String.format String "%.8f" m String[] args args public class Main {

    public static void main(String[] args) throws IOException {
        Scanner in = new Scanner(System.in);
        long l = in.nextLong();

        double c = (double) l / 3;
        double m = c * c * c;
        System.out.println(String.format("%.8f",m));
    }
} public class Main {

    public static void main(String[] args) throws IOException {
        Scanner in = new Scanner(System.in);
        long l = in.nextLong();

        double c = (double) l / 3;
        double m = c * c * c;
        System.out.println(String.format("%.8f",m));
    }
} Main
import java.io.IOException;
import java.util.*;

public class Main {

    public static void main(String[] args) throws IOException {
        Scanner in = new Scanner(System.in);
        long l = in.nextLong();

        double c = (double) l / 3;
        double m = c * c * c;
        System.out.println(String.format("%.8f",m));
    }
}