static void Main() { // Date until workdays DateTime date = new DateTime(2015, 03, 15); List <DateTime> holidays = new List <DateTime>() { new DateTime(2015, 02, 14), // Valentine's Day new DateTime(2015, 03, 03), // National praznik new DateTime(2015, 05, 06) // Gergiovden }; Console.WriteLine("Workdays: {0}", Workdays.NumberOfWorkDays(date, holidays)); }