using System.Collections;
using System.Globalization;
using static Program.Program;


namespace Program
{
    class Program
    {
        static void Main(string[] args)
        {
            NumberCollection numbers = new NumberCollection();

            foreach (var number in numbers.Numbers)
            {
                Console.WriteLine(number);
            }

            foreach (var number in numbers.Numbers2)
            {
                Console.WriteLine(number);
            }


            NumberCollection2 numbers2 = new NumberCollection2();

            foreach (var number in numbers2)
            {
                Console.WriteLine(number);
            }
        }

        public class NumberCollection
        {
            private int[] numbers;

            public NumberCollection(int n = 1000)
            {
                numbers = new int[n];
                for (int i = 0; i < numbers.Length; i++)
                {
                    numbers[i] = i + 1;
                }
            }

            public int[] Numbers => numbers;

            public IEnumerable<int> Numbers2 {
                get
                {
                    yield return 1;
                    yield return 2;
                    yield return 3;
                    yield return 4;
                    yield return 5;
                } }
        }

        public class NumberCollection2 : IEnumerable
        {
            private int[] numbers;

            public NumberCollection2(int n = 1000)
            {
                numbers = new int[n];
                for (int i = 0; i < numbers.Length; i++)
                {
                    numbers[i] = i + 1;
                }
            }

            public IEnumerator GetEnumerator()
            {
                for (int i = 0;i < numbers.Length; i++)
                {
                    yield return numbers[i];
                }
            }
        }

    }
}