from functools import reduce
import operator

Q = int(input().strip())
S = set()
for _ in range(Q):
    query = list(map(int, input().strip().split()))
    if query[0] == 1:
        S.add(query[1])
    elif query[0] == 2:
        if query[1] in S:
            S.remove(query[1])
    elif query[0] == 3:
        if not S:
            print(-1)
        else:
            result = reduce(operator.and_, S)
            print(result)