using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var startDate = new DateTime(2020, 2, 15);

        var endDate = new DateTime(2020, 12, 31);

        var yearMonths = GetYearMonths(startDate, endDate);

        foreach (var yearMonth in yearMonths) 

        {

            Console.WriteLine(yearMonth);

        }

        //Console.WriteLine(string.Join(", ", yearMonths));

    }

     private static IEnumerable<(int Year, int Month)> GetYearMonths(DateTime startDate, DateTime endDate)

        {

            //List<(int Year, int Month)> yearMonths = new();

​

            while (startDate <= endDate)

            {

                //yearMonths.Add((startDate.Year, startDate.Month));

​

                yield return (startDate.Year, startDate.Month);

                startDate = startDate.AddMonths(1);

            }

​

            //return yearMonths;

        }

}