using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Zad4
{
    class ParkingEvent : EventArgs
    {
        public readonly int oldQuantity,NewQuantity;

        public ParkingEvent(int oldQuantity, int NewQuaintity)
        {
            this.oldQuantity = oldQuantity;
            this.NewQuantity = NewQuaintity;
        }
    }
    class Parking
    {
        int stan;

        public EventHandler<ParkingEvent> Change;

        public void change(ParkingEvent e)
        {
            Change?.Invoke(this,e);
        }

        public Parking(int stan)
        {
            this.stan = stan;
        }

        public int Wjazd
        {
            get { return stan; }
            set
            {
                int temp = stan;
                stan += value;
                change(new ParkingEvent(temp,stan));
            }
        }

        public int Wyjazd
        {
            get { return stan; }
            set
            {
                int temp = stan;
                stan -= value;
                change(new ParkingEvent(temp,stan));
            }
        }

    }
    class Program
    {
        static void QuantityChanged(object sender, ParkingEvent e)
        {
            int roznica = e.NewQuantity - e.oldQuantity;
            if (roznica > 0) Console.WriteLine("Wjechało {0} nowych pojazdów. Na parkingu znajduje sie obecnie {1}. ",roznica,e.NewQuantity);
            else Console.WriteLine("Wyjechało {0} pojazdów. Na parkingu znajduje się obecnie {1}. ",-roznica,e.NewQuantity);
        }
        static void Main(string[] args)
        {
            Parking p = new Parking(100);
            p.Change += QuantityChanged;

            p.Wjazd = 10;
            p.Wyjazd = 60;
            p.Wjazd = 50;
            Console.ReadKey();
        }
    }
}