using System;

public class Program

{

    public static void Main()

    {

​

       int totalWorkingDaysInMonth = GetWorkingDays(DateTime.Now.AddDays(-31),DateTime.Now);

        Console.WriteLine(totalWorkingDaysInMonth);

​

    }

    public static int GetWorkingDays(DateTime dtmStart, DateTime dtmEnd) 

    { 

        // This function includes the start and end date if it falls on a weekday 

        int dowStart = ((int)dtmStart.DayOfWeek == 0 ? 7 : (int)dtmStart.DayOfWeek); 

        int dowEnd = ((int)dtmEnd.DayOfWeek == 0 ? 7 : (int)dtmEnd.DayOfWeek); 

        TimeSpan tSpan = dtmEnd - dtmStart; 

        if (dowStart <= dowEnd) 

        { 

        return (((tSpan.Days / 7) * 5) + Math.Max((Math.Min((dowEnd + 1), 6) - dowStart), 0)); 

        } 

        else 

        { 

        return (((tSpan.Days / 7) * 5) + Math.Min((dowEnd + 6) - Math.Min(dowStart, 6), 5)); 

        } 

    } 

}