using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello Diego");

        int grade;

        Console.WriteLine("Input class grade: ");

        grade = Convert.ToInt32(Console.ReadLine());

        string classification;

        switch (grade)

        {

            case 1:

            case 2:

            case 3:

            case 4:

            case 5:

                classification = "grade-schooler";

                break;

            case 6:

            case 7:

            case 8: 

                classification = "Middle-schooler";

                break;

            case 9:

                classification = "freshman";

                break;

            case 10: 

                classification = "sophomore";

                break;

            case 11:

                classification = "junior";

                break;

            case 12:

                classification = "senior";

                break;

            default:

                classification = "undefined";

                break;

        }

        if(classification == "undefined")

        {

            Console.WriteLine("...invalid grade...");

        }

        else

        {

        Console.WriteLine("Student is a {0}.", classification);

        }

    }

}