用两个栈实现一个队列。队列的声明如下，请实现它的两个函数 appendTail 和 deleteHead ，分别完成在队列尾部插入整数和在队列头部删除整数的功能。(若队列中没有元素，deleteHead 操作返回 -1 )

示例 1：

输入：
["CQueue","appendTail","deleteHead","deleteHead"]
[[],[3],[],[]]
输出：[null,null,3,-1]
示例 2：

输入：
["CQueue","deleteHead","appendTail","appendTail","deleteHead","deleteHead"]
[[],[],[5],[2],[],[]]
输出：[null,-1,null,null,5,2]

#剑指 Offer 09 题目解析
#进栈：stack.append(1)   出栈：stack.pop()      先进后出
#进队：queue.append(1)   出队：queue.popleft()  先进先出   from collections import deque


class CQueue:
	def __init__(self):
		self.A = []
		self.B = []
	def appendTail(self, value) -> None:
		self.A.append(value)

	def deleteHead(self) -> int:
		if self.B:
			return self.B.pop()
		if not self.A:
			return -1
		while self.A:
			self.B.append(self.A.pop())
		return self.B.pop()
# Your CQueue object will be instantiated and called as such:
obj = CQueue()
obj.appendTail("one")
obj.appendTail("two")
obj.appendTail("three")
print("处理前：")
print("obj.A=",str(obj.A))

param_2 = obj.deleteHead()

print("处理后：")
print("obj.A=",str(obj.A))
print("obj.B=",str(obj.B))