from collections import deque
d=deque()
for _ in range(int(input())):
    n=input().split()
    if n[0]=="append":
        d.append(int(n[-1]))
    elif n[0]=="appendleft":
        d.appendleft(int(n[-1]))
    elif n[0]=="pop":
        d.pop()
    elif n[0]=="popleft":
        d.popleft()
print(" ".join(map(str, list(d))))