백준 10828 파이썬

n = int(input())

a=[]

for i in range(n):

cmd = input().split()

if cmd[0] == 'push':

a.append(cmd[1])

elif cmd[0] == 'pop':

try:print(a.pop())

except: print(-1)

elif cmd[0] == 'size':

print(len(a))

elif cmd[0] == 'empty':

if len(a)==0:

print(1)

else:

print(0)

elif cmd[0] == 'top':

try:

print(a[-1])

except:

print(-1)