#include <iostream>
#include <cstdint>
#include <vector>
#include <set>
#include <array>
#include <climits>

using namespace std;

int main()
{
	cin.tie(nullptr);
	ios::sync_with_stdio(false);

	uint32_t Q, i;
	cin >> Q;
	vector<pair<char, uint32_t>> query(Q);
	for (i = 0; i != Q; ++i)
	{
		cin >> query[i].first;
		if (query[i].first != '3') cin >> query[i].second;
	}

	set<uint32_t> S;
	set<uint32_t>::iterator itr;
	array<uint32_t, CHAR_BIT * sizeof(query[0].second)> bitwise_counter;
	uint32_t ans;
	bitwise_counter.fill(0);
	for (i = 0; i != Q; ++i)
		switch (query[i].first)
		{
		case '1':
			itr = S.lower_bound(query[i].second);
			if (*itr != query[i].second)
			{
				S.emplace_hint(itr, query[i].second);
				for (uint8_t j = 0; j != bitwise_counter.size(); ++j)
					if ((query[i].second >> j) & 1) ++bitwise_counter[j];
			}
			break;

		case '2':
			itr = S.find(query[i].second);
			if (itr != S.end())
			{
				S.erase(itr);
				for (uint8_t j = 0; j != bitwise_counter.size(); ++j)
					if ((query[i].second >> j) & 1) --bitwise_counter[j];
			}
			break;

		case '3':
			if (S.empty()) cout << "-1\n";
			else
			{
				ans = 0;
				for (uint8_t j = 0; j != bitwise_counter.size(); ++j)
					if (bitwise_counter[j] == S.size()) ans |= UINT32_C(1) << j;
				cout << ans << '\n';
			}
		}

	return 0;
}