program DayCodeDriver;
{Reads the day of January 1 and the year and prints calendar.
  Demo for stubs, drivers, and enumerated types.}

type DayType = (Sun, Mon, Tue, Wed, Thu, Fri, Sat);
     WeekdayType = Mon..Fri;
     MonthType = (Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec);
     YearType = 1500..2500; {valid for Gregorian calendar}

var  Year : Yeartype; {input - the calendar year}
     StartDay : Daytype; {input - New Year's Day}
     DayCh1,DayCh2,DayCh3 : Char; {input - letters in day name}
     Month : MonthType; {the current month}
     FebFlag : Boolean; {true for leap years}

procedure DayCode(Ch1,Ch2: Char; var Day : DayType);
{stub of day conversion - returns Sun or Mon}
     begin
       case Ch1 of
        'S','s' : if (Ch2 = 'u') or (Ch2 = 'U') then
                    Day := Sun
                  else if (Ch2 = 'a') or (Ch2 = 'A') then
                    Day := Sat
                  else
                    WriteLn('BadDayCode');
        'M','m' : Day := Mon;
        'T','t' : if (Ch2 = 'u') or (Ch2 = 'U') then
                    Day := Tue
                  else if (Ch2 = 'h') or (Ch2 = 'H') then
                    Day := Thu
                  else
                    WriteLn('BadDayCode');
        'W','w' : Day := Wed;
        'F','f' : Day := Fri
        else WriteLn('BadDayCode')
        end{Case Ch1};
     end;{DayCode}


begin{main program}
     WriteLn('Use the first 3 letters to identify the day.');
     ReadLn(DayCh1, DayCh2, DayCh3);
     DayCode(DayCh1,DayCh2,StartDay);
end.