백준 10845 파이썬

i = int(input())

queue =[]

for j in range(i):

cmd = input().split()

if cmd[0] == 'push':

queue.append(cmd[1])

elif cmd[0] == 'pop':

if len(queue) !=0:

print(queue.pop(0))

else:

print(-1)

elif cmd[0] == 'size':

print(len(queue))

elif cmd[0] == 'empty':

if len(queue) == 0:

print(1)

else:

print(0)

elif cmd[0] == 'front':

if len(queue) !=0:

print(queue[0])

else:

print(-1)

elif cmd[0] == 'back':

if len(queue) !=0:

print(queue[-1])

else:

print(-1)