Throwing an exception

Program.cs

using System;

namespace Expections
{
    class Fehler : ApplicationException
    {
        public Fehler() : base()
        {
        }

        public Fehler(string m) : base(m)
        {
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            int i = 10;

            try
            {
                if (i == 10)
                    throw (new Fehler("Error: Zahl ist 10"));
            }
            catch (NotSupportedException ex)
            {
            }
            catch (Fehler ex)
            {
                Console.WriteLine(ex.Message);
            }
            finally
            {
                Console.ReadKey();
            }
        }
    }
}