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

namespace ConsoleApp38
{
   struct Point
    {
        int x;
        int y;

        public Point(int x, int y)
        {
            this.x = x;
            this.y = y;
        }

        public override string ToString()
        {
            return $" X: {x}  Y: {y}";
        }

        public int X
        {
            get { return x;  }
            set { x = value; }
        }

        public int Y
        {
            get { return y;  }
            set { y = value; }
        }

        public static Point operator -(Point p1, Point p2)
        {
            return new Point { x = p1.x - p2.x, y = p1.y - p2.y };
        }

    }

    class PointList : IEnumerable
    {
        private Point[] P;

        public PointList(Point[] List)
        {
            P = List;
            Count = P.Length;
        }

        public int Count { get; set; }

        public void Add(Point item)
        {
            Point[] temp = new Point[P.Length + 1];
            for (int i=0; i < P.Length; i++)
            {
                temp[i] = P[i];
            }
            P = temp;
            P[Count] = item;
            Count++;
        }

        public void Del()
        {
            Point[] temp = new Point[P.Length - 1];
            for (int i = 0; i < P.Length - 1; i++)
            {
                temp[i] = P[i];
            }
            P = temp;
            Count--;
        }

        public void DelAt(int index)
        {
            Point[] temp = new Point[P.Length - 1];
            int Counter = 0;
            for (int i = 0; i < P.Length - 1; i++)
            {
                if (i != index) { temp[Counter] = P[i]; Counter++; }
            }
            P = temp;
            Count--;
        }

        public void Array()
        {
            Console.WriteLine("-----------");

            for (int i=0; i < P.Length; i++)
            {
                Console.WriteLine(P[i]);
            }

            Console.WriteLine("-----------");
        }

        public Point this[int index]
        {
            get {return P[index];}
        }

        public IEnumerator GetEnumerator()
        {
            return P.GetEnumerator();
        }
    }

    class Points
    {
        private Point[] P;
        public Points(int capacity)
        {
            P = new Point[capacity];
            Count = 0;
            Capacity = capacity;
        }

        public int Count { get; set; }
        public int Capacity { get; set; }

        public void Add(Point item)
        {
            if (Count+1 > Capacity)
            {
                Point[] temp = new Point[Capacity + 5];
                for (int i=0; i < Capacity; i++)
                {
                    temp[i] = P[i];
                }
                Capacity += 5;
                temp[Count] = item;
                Count++;
            }
            else
            {
                P[Count] = item;
                Count++;
            }
        }

        public void Del()
        {
            Point[] temp = new Point[Count - 1];
            for(int i = 0; i < Count - 1; i++)
            {
                temp[i] = P[i];
            }
            P = temp;
            Capacity = Count - 1;
            Count--;
        }

        public void DelAt(int index)
        {
            Point[] temp = new Point[P.Length - 1];
            int Counter = 0;
            for (int i = 0; i < P.Length - 1; i++)
            {
                if (i != index) { temp[Counter] = P[i]; Counter++; }
            }
            P = temp;
            Count--;
            Capacity--;
        }

        public void Array()
        {
            Console.WriteLine("***********");

            for (int i = 0; i < P.Length; i++)
            {
                Console.WriteLine(P[i]);
            }

            Console.WriteLine("***********");
        }

        public Point this[int index]
        {
            get {return P[index];}
        }

        public IEnumerator GetEnumerator()
        {
            return P.GetEnumerator();
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            Point point1 = new Point(10, 5);
            Point point2 = new Point(9, 4);
            Point point3 = point1 - point2;

            Console.WriteLine("Point 1   " + point1);
            Console.WriteLine("Point 2   " + point2);
            Console.WriteLine("Point 1 - Point 2    " + point3);
            Console.WriteLine();

            Point[] list = new Point[2] { point1, point2 };
            PointList ptList = new PointList(list);

            ptList.Add(point3);
            ptList.Array();

            Point point4 = new Point(20, 15);
            Point point5 = new Point(10, 5);
            Point point6 = point4 - point5;
            Console.WriteLine("Point 4   " + point4);
            Console.WriteLine("Point 5   " + point5);
            Console.WriteLine("Point 4 - Point 5    " + point6);
            Console.WriteLine();

            Points L = new Points(5);
            L.Add(point4);
            L.Add(point5);
            L.Add(point6);
            L.Array();

            Console.ReadKey();
        }
    }
}