OOP Sealed Class

using System;


namespace TestClassOOP
{
    class Program
    {
        sealed  class Tiger
        {
            public void show()
            {

                Console.WriteLine("Sealed class !");
            }
        }
        class Dog:Tiger
        {
            // Error: can't derive from sealed type 'Tiger'
        }
        static void Main(string[] args)
        {
            Tiger tg = new Tiger();
            tg.show();

            Console.ReadLine();

        }
    }
}