IMPLEMENT_QUEUE_USING_STACK_MAKING_DEQUEUE_COSTLY

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

class Queue:
	def __init__(self):
		self.s1=[]
		self.s2=[None]


	# EnQueue an item into the queue
	def enQueue(self,value):
		self.s1.append(value)
		


	# Dequeue an item from the queue
	def deQueue(self):
		if len(self.s2) == 0:
			return "Queue is empty"
		else:
			# Move all elements from s1 to s2  
			self.s2=[]
			for i in range(len(self.s1)-1,-1,-1):
				self.s2.append(self.s1[i])

			val=self.s2[len(self.s2)-1]
			self.s2=self.s2[:len(self.s2)-1]
			self.s1=self.s1[1:]
			
			return val



q=Queue()

q.enQueue(1)
q.enQueue(2)
q.enQueue(3)
q.enQueue(4)
q.enQueue(5)
print(q.deQueue())
print(q.deQueue())
print(q.deQueue())
print(q.deQueue())
print(q.deQueue())
print(q.deQueue())