# Ask the user for a day, month, and year.
day   = int(input("Enter a day (1-31): "))
month = int(input("Enter a month (1-12): "))
year  = int(input("Enter a year (0 to 2099): "))

# Determine if it's a leapyear.
isLeapYear = ((year % 4 == 0) and not(year % 100 == 0)) or (year % 400 == 0)

# Determine if it's a valid date.    
if month == 2:
    daysInMonth = 29 if isLeapYear else 28
elif month in (4, 6, 9, 11):
    daysInMonth = 30
else:
    daysInMonth = 31

isvalid =  day >= 1 and day <= daysInMonth and \
           month >= 1 and month <= 12 and \
           year >= 0 and year <= 2099
print("%02d/%02d/%04d valid? %s" % (day, month, year, isvalid))

# Determine the name of the month.        
if month == 1:
    monthName = "January" 
elif month == 2: 
    monthName = "February" 
elif month == 3: 
    monthName = "March" 
elif month == 4: 
    monthName = "April" 
elif month == 5: 
    monthName = "May" 
elif month == 6: 
    monthName = "June" 
elif month == 7: 
    monthName = "July" 
elif month == 8: 
    monthName = "August" 
elif month == 9: 
    monthName = "September" 
elif month == 10: 
    monthName = "October" 
elif month == 11: 
    monthName = "November" 
elif month == 12: 
    monthName = "December" 
else:
    monthName = "Not Known"     # Should never happen

# Display all the dates in the month.
print("Dates in %s, %d" % (monthName, year))
for day in range(1, daysInMonth+1):

    if day in (1, 21, 31):
        suffix = "st"
    elif day in (2, 22):
        suffix = "nd"
    elif day in (3, 23):
        suffix = "rd"
    else:
        suffix = "th"
        
    print("%d%s %s %d" % (day , suffix, monthName, year))