Queue using Stacks.py

# Python3 program to implement Queue using
# two stacks with costly enQueue()

class Queue:
	def __init__(self):
		self.s1 = []
		self.s2 = []

	def enQueue(self, x):
		
		while len(self.s1) != 0:
			self.s2.append(self.s1[-1])
			self.s1.pop()

		self.s1.append(x)

		while len(self.s2) != 0:
			self.s1.append(self.s2[-1])
			self.s2.pop()

	def deQueue(self):
		
		if len(self.s1) == 0:
			print("Q is Empty")
	
		x = self.s1[-1]
		self.s1.pop()
		return x

if __name__ == '__main__':
	q = Queue()
	q.enQueue(1)
	q.enQueue(2)
	q.enQueue(3)

	print(q.deQueue())
	print(q.deQueue())
	print(q.deQueue())