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

namespace DelegateandObserver
{
   public  class Cat
    {
        private Observer ob;

        public Cat(Observer ob)
        {
            this.ob = ob;
        }

        public void Cry()
        {
            Console.WriteLine("Cat is crying...");
            ob.Do();
        }
    }
}