s1 = []
s2 = []

def enq(val):
	global s1, s2
	if len(s1) == 0:
		s1.append(val)
	else:
		s2.append(val)
		while len(s1) > 0:
			s2.append(s1.pop())
		s1, s2 = s2, s1

def empty():
	global s1, s2
	return len(s1) == 0 and len(s2) == 0

def deq():
	global s1, s2
	if empty():
		print("he's dead, jim")
	return s1.pop()

size = 5

for i in range(size):
	enq((i+1)*10)

for i in range(size):
	print(deq())