class Stack(object):

    def __init__(self):

        self.stack = []

    def push(self, value): # 进栈

        self.stack.append(value)

    def pop(self):  # 出栈

        if self.stack :

            self.stack.pop()

        else:

            raise LookupError("stack is empty")

    def is_empty(self):  # 如果栈为空

        return bool(self.stack)

    def top(self):

        # 取出目前stack中最新的元素

        return self.stack[-1]

class Node:

    def __init__(self,data):

        self.data=data

        self.next=None

class Queue:

    def __init__(self):

        self.rear=None

        self.front=None

        self.r=0

        self.f=0

    def isEMpty(self):

        if self.r==self.f:

            print("The queue is empty")

        else:

            print("The queue is not empty")

    def push(self,data):

        if self.f==self.r:

            q=Node(data)

            self.rear=q

            self.front=q

            self.r=0

            self.f=1

        else:

            q=Node(data)

            self.rear.next=q

            self.rear=q

            self.f+=1

    def pop(self):

        if self.r==self.f:

            print("The Queue is empty")

            #return false

        else:

            self.front=self.front.next

            self.f=self.f-1

    def top(self):

        if self.r==self.f:

            print("empty")

        else:

            print(self.front.data)