using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var startDate = DateTime.Today.AddDays(10);

        var endDate = startDate.AddDays(100);

        var days = (int) (endDate - startDate).TotalDays;

        var dayOfWeek = DayOfWeek.Monday;

        var dates =

            Enumerable.

                Range(0, days)

                .Select(n => startDate.AddDays(n))

                .Where(d => d.Date == startDate || d.DayOfWeek == dayOfWeek)

                .ToArray();

        Console.WriteLine("Starting from {0:dd.MM.yyyy} ({1}) and ending on {2:dd.MM.yyyy} ({3}), payments go:", startDate, startDate.DayOfWeek, endDate, endDate.DayOfWeek);

        foreach(var date in dates)

            Console.WriteLine("Payment on {0:dd.MM.yyy} ({1})", date, date.DayOfWeek);

    }

}