import datetime


class Person(object):
    def __init__(self, name):
        self.name = name
        try:
            lastBlank = name.rindex(' ')
            self.lastName = name[lastBlank + 1:]
        except:
            self.lastName = name
        self.birthday = None

    def getName(self):
        return self.name

    def getLastName(self):
        return self.lastName

    def setBirthday(self, birthday):
        self.birthday = birthday

    def getAge(self):
        if self.birthday == None:
            raise ValueError
        return (datetime.date.today() - self.birthday).days

    def __lt__(self, other):
        if self.lastName == other.lastName:
            return self.name < other.name
        return self.lastName < other.lastName

    def __str__(self):
        return self.name

class mitPerson(Person):
    nextidnum = 0

    def __init__(self, name):
        self.idnum = mitPerson.nextidnum
        mitPerson.nextidnum += 1

    def getidnum(self):
        return self.idnum

    def __lt__(self, other):
        return self.idnum < other.idnum


p1 = mitPerson('barbara beaver')
print(str(p1) + '\'s id number is ' + str(p1.getidnum()))