백준 10866번 파이썬

num = int(input())

a=[]

for i in range(num):

cmd = input().split()

if cmd[0] == 'push_front':

a.insert(0,cmd[1])

elif cmd[0] == 'push_back':

a.append(cmd[1])

elif cmd[0] == 'pop_front':

if len(a)!=0:

print(a.pop(0))

else:

print(-1)

elif cmd[0] == 'pop_back':

if len(a)!=0:

print(a.pop(-1))

else:

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] == 'front':

if len(a)==0:

print(-1)

else:

print(a[0])

elif cmd[0] == 'back':

if len(a)==0:

print(-1)

else:

print(a[-1])