import java.util.Scanner;

public class Main{
    public static void main(String[] args) {
        Scanner stdIn = new Scanner(System.in);

        double l = stdIn.nextDouble();

        System.out.println(l*l*l/27);
    }
} import java.util.Scanner; Scanner java.util public class Main{
    public static void main(String[] args) {
        Scanner stdIn = new Scanner(System.in);

        double l = stdIn.nextDouble();

        System.out.println(l*l*l/27);
    }
} Main public static void main(String[] args) {
        Scanner stdIn = new Scanner(System.in);

        double l = stdIn.nextDouble();

        System.out.println(l*l*l/27);
    } main {
        Scanner stdIn = new Scanner(System.in);

        double l = stdIn.nextDouble();

        System.out.println(l*l*l/27);
    } Scanner stdIn = new Scanner(System.in); stdIn new Scanner(System.in) double l = stdIn.nextDouble(); l stdIn.nextDouble() stdIn.nextDouble stdIn System.out.println(l*l*l/27) System.out.println System.out System System.out l*l*l/27 l*l*l l*l*l l l l 27 String[] args args public class Main{
    public static void main(String[] args) {
        Scanner stdIn = new Scanner(System.in);

        double l = stdIn.nextDouble();

        System.out.println(l*l*l/27);
    }
} public class Main{
    public static void main(String[] args) {
        Scanner stdIn = new Scanner(System.in);

        double l = stdIn.nextDouble();

        System.out.println(l*l*l/27);
    }
} Main
import java.util.Scanner;

public class Main{
    public static void main(String[] args) {
        Scanner stdIn = new Scanner(System.in);

        double l = stdIn.nextDouble();

        System.out.println(l*l*l/27);
    }
}