출처 | https://www.acmicpc.net/status?user_id=ohjihwan123&problem_id=10845&from_mine=1

코드

import sys 

input = sys.stdin.readline
N= int(input())
Que = []

for i in range(N):
  com = input().split()

  if com[0] == "push":
    Que.append(com[1])

  elif com[0] == "pop":
    if Que:
      print(Que.pop(0)) # 0번째 pop
    else:
      print(-1)
  elif com[0] == "size":
    print(len(Que))

  elif com[0] == "empty":
    if len(Que) == 0:
      print(1)
    else:
      print(0)

  elif com[0] == "front":
    if len(Que) == 0:
      print(-1)
    else:
      print(Que[0])
  
  elif com[0] == "back":
    if len(Que) == 0:
      print(-1)
    else:
      print(Que[-1])