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