{
    Return the number of days in the given month in the given year.
}
function NumberOfDaysIn (month, year: integer): integer;

    {
	Return 0 to represent no leap day, or 1 if it's a leap year. 
    }
    function LeapDay (year: integer): integer;
    begin
	if (year mod 4 = 0) and (year mod 100 <> 0) then begin
	    LeapDay := 1
	end else if year mod 400 = 0 then begin
	    LeapDay := 1
	end else begin
	    LeapDay := 0;
	end;
    end;

begin {NumberOfDaysIn}
    case month of
	JAN, MAR, MAY, JUL, AUG, OCT, DEC: 
	    NumberOfDaysIn := 31;
	FEB: 
	    NumberOfDaysIn := 28 + LeapDay (year);
	APR, JUN, SEP, NOV: 
	    NumberOfDaysIn := 30;
    end;
end   {NumberOfDaysIn};