from collections import deque

d = deque()
n = int(input())
for _ in range(n):
    string = input().split(' ')
    if string[0] == "append":
        d.append(string[1])
    elif string[0] == "appendleft":
        d.appendleft(string[1])
    elif string[0] == "pop":
        d.pop()
    else:
        d.popleft()
print(*d, end=" ")