[백준/파이썬]10828번 스택

-코드

from sys import stdin
r = []
n = int(stdin.readline())
for i in range(n):
    a = stdin.readline().split()
    if a[0] == 'push':
        r.append(a[1])
    elif a[0] == 'pop':
        if len(r) == 0:
            print(-1)
        else:
            print(r.pop())
    elif a[0] == 'size':
        print(len(r))
    elif a[0] == 'empty':
        if len(r) == 0:
            print(1)
        else:
            print(0)
    elif a[0] == 'top':
        if len(r) == 0:
            print(-1)
        else:
            print(r[len(r) - 1])