S = set()
Q = int(input())
v = [0] * 30
for _ in range(Q):
	t = list(map(int,input().split()))
	if t[0] == 1:
		x = t[1]
		if x in S: continue
		for i in range(30):
			if x >> i & 1:
				v[i] += 1
		S.add(x)
	elif t[0] == 2:
		x = t[1]
		if x not in S: continue
		for i in range(30):
			if x >> i & 1:
				v[i] -= 1
		S.remove(x)
	else:
		ret = 0
		r = len(S)
		if r == 0:
			print(-1)
			continue
		for i in range(30):
			if v[i] == r:
				ret += 1 << i
		print(ret)