using System;

using System.Linq;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        var a = Convert.ToDateTime("1-MAR-2023");

        var b= Convert.ToDateTime("15-APR-2023");

        var c = (b-a).TotalDays;

        var cnt = Math.Truncate(c/30) + (c%30 > 0 ? 1 : 0);

        var dates = new List<Range>();

        for(var i = 0; i < cnt; i++){

            DateTime? lastEndDate = dates.OrderByDescending(x => x.EndDate).Select(x => x.EndDate)?.FirstOrDefault();

            var date = new Range(){

                StartDate = lastEndDate == null ? a : Convert.ToDateTime(lastEndDate),

                EndDate = Convert.ToDateTime(lastEndDate).AddDays(30)

            };

            Console.WriteLine(Convert.ToDateTime(lastEndDate).ToShortDateString());

        }

    }

}

public class Range{

    public DateTime StartDate{get;set;}

    public DateTime EndDate{get;set;}

    }