class Node():
    def __init__(self, value, next= None):
        self.value = value
        self.next = next


class AnimalShelter():

    def __init__(self):
        self.first = None
        self.last = None

    def enqueue(self, value):
        pass

    def dequeue(self, pref):
        pass



class Node():
    def __init__(self, value, next= None):
        self.value = value
        self.next = next


class AnimalShelter():

    def __init__(self):
        self.first = None
        self.last = None

    def enqueue(self, value):
        pass

    def dequeue(self, pref):
        pass


