import collections
de = collections.deque()
f1 = open("output.txt", "w")
with open("input.txt") as f:
for i in range(1):
x = f.readline()
x = int(x)
q = 0
for j in range(x):
q += 1
for k in range(q):
a = f.readline().split()
if a == 1 or a == 2:
a, b = f.readline().split()
if a == 1:
de.appendleft(b)
elif a == 2:
de.append(b)
elif a == 3:
b = str(b)
f1.write(b + " ")
b = int(b)
de.popleft()
elif a == 4:
b = str(b)
f1.write(b + " ")
b = int(b)
de.pop()
f.close()
f1.close()