program PrMonDr;
{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, Thur, 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 PrintMonth(Month: MonthType; var StDay : DayType);
{the main procedure}
  type MLType = 28..31;

  var ML : MLType;

  procedure PrintWeeks(MLFP : MLType; var StDFP : DayType);

   var Day : DayType;
       DayNum : 1.. 31;

   begin
   {First Week:}
     WriteLn;
     Day := Sun; DayNum := 1;
     while Day < StDFP do
      begin
        Write('    ');
        Day := Succ(Day)
      end;
     for Day := StDFP to Sat do
       begin
         Write(DayNum :4);
         Daynum := DayNum + 1
       end;
    WriteLn; WriteLn;
    {Later Weeks:}
    while DayNum + 6 <= ML do
     begin
      for Day := Sun to Sat do
        begin
          Write(DayNum : 4);
          Daynum := DayNum + 1;
        end;{for}
       WriteLn;WriteLn;
     end;
    {Last Week}
    StDFP := Sun;
    while DayNum <= ML do
     begin
       Write(DayNum :4);
       StDFP := Succ(StDFP);
       DayNum := DayNum +1
     end
  end;{PrintMonth}


     begin
       {MonthHeading(Month);}
       {ML := MonLen(Month);}
       ML := 31;
       PrintWeeks(ML, StDay)
     end;

begin{main program}
       FebFlag := False;
     StartDay := Mon;
     for Month := Jan to Dec do
       PrintMonth(Month,StartDay);
end.