using System;

public class Program

{

       [Flags]

       enum Days

    { 

           NoClasses = 0,

           Monday = 1,

           Tuesday = 2,

           Wednesday = 4,

           Thursday = 8,

           Friday = 16,

           Saturday = 32,

           Sunday = 64

       }

       public static void Main(string[] args)

        {

             Days student=Days.NoClasses ;// байт хранение расписания

            int checker=9;

            int dayChecker=0;

            bool checkResult;

            // блок ввода расписания 

            Console.WriteLine(" Let make the week schedule");

            MakeSchedule();

           while (checker!=0)

           {

              Console.WriteLine("Input number of day from 1 to 7 to check schedule for a day");

              Console.WriteLine("Input 8 to see whole week schedule");

              Console.WriteLine("Input 0 to exit");

              checker=CheckInput(0,8);

             switch(checker)

             {

               case 0:

                    break;

               case 8:

               Console.WriteLine("Classes will be on the following days: {0}", student);

                   break;

               default:

                    dayChecker=1<<checker-1;

                    checkResult=(Days)dayChecker==(student&(Days)dayChecker);

                 Console.WriteLine("In the {0} {1} classes",(Days)dayChecker, checkResult==true? "will be" : "wil not be" );

                   break;

               }

           }

       }

    public static void MakeSchedule()

    {

        string schedule;

        string [] schedule1;

        Days student=Days.NoClasses;

        Console.WriteLine(" Input number of days when there are classes");

        Console.WriteLine(" Number of days starting from 1 for Monday to 7 for Sunday");

        Console.WriteLine(" Each number shall be separeted by coma");

        Console.WriteLine(" For example: 1,5,7 means that the classes will be on Monday, Friday and Sunday");

        schedule = Console.ReadLine();

        schedule1=schedule.Split(',');

        foreach ( string s in schedule1)

        {   

            int s2=0;

             s2=1<<Convert.ToInt32(s)-1;

            student=student|(Days)s2;

        }

    }

    public static int CheckInput(int s, int f)

    {

        bool result=false; 

        int input=0; 

        do

         {

        result = Int32.TryParse(Console.ReadLine(), out input);

         if (!result | input>f | input<s )

           {

              Console.WriteLine("Invalid input");         

           }

         }

        while (!result | input>f | input<s );

    return input;

    }

   }

​