static void Main(string[] args)
        {   //The 1st day of current month
            DateTime DatePointer = new DateTime(DateTime.Now.Year, DateTime.Now.Month, 1);

            //workday counter
            Int32 WorkdayCounter = 0;

            //Loop until the datepointer is the current date
            do
            {
                if(isWorkday(DatePointer))
                    WorkdayCounter++;          
      
                DatePointer = DatePointer.AddDays(1);
            } while (DatePointer <= DateTime.Today && WorkdayCounter < 23);

            //Amount of workday is max 23, and if today is weekend, it's no workday
            if (WorkdayCounter <= 23 && (isWorkday(DateTime.Now)))
                System.Console.WriteLine(WorkdayCounter.ToString());
            else
                System.Console.WriteLine("-1");
        }

        /// <summary>
        /// check if a date is a workday
        /// </summary>
        /// <param name="chkDate">the date to check</param>
        /// <returns>boolean, true = workday, false != workday </returns>
        static bool isWorkday(DateTime chkDate)
        {
            if(chkDate.DayOfWeek== DayOfWeek.Saturday ||chkDate.DayOfWeek== DayOfWeek.Sunday)
                return false;
            else
                return true;
        }