[백준] 28279 덱2

import sys
from collections import deque

n = int(sys.stdin.readline())
deque2 = deque([])
for i in range(n):
    data = list(map(int,sys.stdin.readline().split()))

    if data[0] == 1:
        deque2.appendleft(data[1])

    if data[0] == 2:
        deque2.append(data[1])

    if data[0] == 3:
        print(-1 if len(deque2) == 0 else deque2.popleft())

    if data[0] == 4:
        print(-1 if len(deque2) == 0 else deque2.pop())

    if data[0] == 5:
        print(len(deque2))

    if data[0] == 6:
        print(1 if len(deque2)==0 else 0)

    if data[0] == 7:
        print(-1 if len(deque2)==0 else deque2[0])

    if data[0] == 8:
        print(-1 if len(deque2)==0 else deque2[-1])