from collections import defaultdict


def main():
    S = set()
    S_bit_digit = [0 for _ in range(30)]

    for _ in range(int(input())):
        query = input().split()
        if len(query) == 1:
            query_type = 3
        else:
            query_type, x = map(int, query)

        if query_type == 1:
            if x in S:
                continue
            S.add(x)

            digit_idx = 0
            while x > 0:
                if x & 1:
                    S_bit_digit[digit_idx] += 1
                x >>= 1
                digit_idx += 1

        elif query_type == 2:
            if x not in S:
                continue
            S.remove(x)

            digit_idx = 0
            while x > 0:
                if x & 1:
                    S_bit_digit[digit_idx] -= 1
                x >>= 1
                digit_idx += 1
        elif query_type == 3:
            if not S:
                print(-1)
            else:
                bitwise_ = 0
                for digit_idx, digit_value in enumerate(S_bit_digit):
                    if digit_value == len(S):
                        bitwise_ += 2 ** digit_idx
                print(bitwise_)
        else:
            raise ValueError


if __name__ == "__main__":
    main()