#include <bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
//using namespace atcoder;
//using mint = modint1000000007;
//const int mod = 1000000007;
//using mint = modint998244353;
//const int mod = 998244353;
//const int INF = 1e9;
//const long long LINF = 1e18;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i,l,r)for(int i=(l);i<(r);++i)
#define rrep(i, n) for (int i = (n-1); i >= 0; --i)
#define rrep2(i,l,r)for(int i=(r-1);i>=(l);--i)
#define all(x) (x).begin(),(x).end()
#define allR(x) (x).rbegin(),(x).rend()
#define endl "\n"
#define P pair<int,int>
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }

int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int q; cin >> q;
	set<int>st;
	vector<int>cnt(30);
	while (q--) {
		int t; cin >> t;
		if (1 == t) {
			int x; cin >> x;
			if (st.count(x))continue;
			st.insert(x);
			rep(i, 30) {
				if (1 & (x >> i))cnt[i]++;
			}
		}
		else if (2 == t) {
			int x; cin >> x;
			if (!st.count(x))continue;
			rep(i, 30) {
				if (1 & (x >> i))cnt[i]--;
			}
			st.erase(x);
		}
		else {
			if (st.empty()) {
				cout << -1 << endl;
				continue;
			}
			int ans = 0;
			rep(i, 30) {
				if (st.size() == cnt[i])ans += 1 << i;
			}
			cout << ans << endl;
		}
	}
	return 0;
}