백준 10828번 스택 Python

N = int(input())
answer = []
stack = []

for _ in range(N):
  cmd = input().split()
  main_cmd = cmd[0]
  if main_cmd == "push":
    stack.append(int(cmd[1]))
  elif main_cmd == "top":
    if stack:
      answer.append(stack[-1])
    else:
      answer.append(-1)
  elif main_cmd == "size":
    answer.append(len(stack))
  elif main_cmd == "empty":
    if stack:
      answer.append(0)
    else:
      answer.append(1)
  else:
    if stack:
      answer.append(stack.pop())
    else:
      answer.append(-1)

for elem in answer:
  print(elem)