#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int,int> P;
#define REP(i,n) for(int i=0;i<int(n);i++)

int b[35];

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


	int Q;
	cin >> Q;
	set<int> s;
	REP(j,Q){
		int q,x;
		cin >> q;

		if(q==1){
			cin >> x;
			if(s.count(x)==1) continue;
			REP(i,31) if(x & (1<<i)) b[i]++;
			s.insert(x);
	    }
		if(q==2 ){
			cin >> x;
			if(s.count(x)==0) continue;
			REP(i,31) if(x & (1<<i)) b[i]--;
			s.erase(x);
		}
		if(q==3){
			int n=s.size(),a=0;
			if(n==0){;
				cout << -1 << endl;
				continue;
			}
			REP(i,31) if(b[i]==n) a+=(1<<i);
			cout << a << endl;
		}

	}



	return 0;
}