q = int(input())

s = set()
bit = [[0 for _ in range(2)] for _ in range(30)]
for _ in range(q):
  t, *args = list(map(int, input().split()))
  if t == 1:
    xi = args[0]
    if not xi in s:
      for i in range(30):
        bit[i][(xi >> i) & 1] += 1
      s.add(xi)
  elif t == 2:
    xi = args[0]
    if xi in s:
      for i in range(30):
        bit[i][(xi >> i) & 1] -= 1
      s.discard(xi)
  elif t == 3:
    if len(s) == 0:
      print("-1")
    else:
      ans = 0
      for i in range(30):
        if bit[i][1] > 0 and bit[i][0] == 0:
          ans |= (1 << i)
      print(ans)