# A Date object represents a month and day such as 12/25.
# This version adds special methods for printing and comparison.

class Date:
    # Constructor initializes the state of new
    # Date objects as they are created by client code.
    def __init__(self, month, day):
        # set the attributes (the state in each Date object)
        self.month = month
        self.day = day

    # Compares dates for equality.
    def __eq__(self, other):
        return self.month == other.month \
        and self.day == other.day

    # Returns a string representation of a Date, such as "9/19".
    def __str__(self):
        return str(self.month) + "/" + str(self.day)

    # Advances the Date's state to the next day,
    # wrapping into the next month/year as necessary.
    def advance(self):
        self.day += 1
        if self.day >= self.days_in_month():
            # wrap to next month
            self.month += 1
            self.day = 1
            if self.month > 12:
                # wrap to next year
                self.month = 1
    
    # Returns the number of days in this Date's month.
    def days_in_month(self):
        if self.month in {4, 6, 9, 11}:
            return 30
        elif self.month == 2:
            return 28
        else:
            return 31