using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var enumerable = GetNumbers();

        enumerable = enumerable.Append(5);

        Console.WriteLine(string.Join(", ", enumerable));

    }

    private static IEnumerable<int> GetNumbers()

    {

        yield return 0;

        yield return 1;

        yield return 2;

        yield return 3;

        yield return 4;

    }

}