using System;
using System.Collections.Generic;
using System.Text;

namespace CsharpBook
{
    public class Starter
    {
        public static void Main()
        {
            ZClass test1 = new ZClass();
            YClass test2 = new YClass();

            YClass.MethodA();
            YClass.MethodA(10);
        }

        public class ZClass
        {
            public virtual void MethodA()
            {
                Console.WriteLine("CsharpBook.MethodA()");
            }
        }

        public class YClass : ZClass
        {
            public override void MethodA(int number)
            {
                Console.WriteLine("CsharpBook.MethodA({0})", number);
            }
        }
    }
}