TRIE

#define NguyenDangQuan the_author
#define my_heart love_you_to_the_moon_and_back

#include <bits/stdc++.h>
#define pb push_back
#define ld long double
#define ll long long
#define ull unsigned long long
#define float double
using namespace std;

int typetest;
inline void fastIOfileinput(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    typetest = 0;
}

struct trie{
    trie *child[2];
    int v;
    void upd(int id, int lim, int u, int x, int val){
        //cerr << lim << " ";
        if(id == lim){
            v += val;
            return;
        }
        if(child[(x >> id) & 1] == nullptr)
            child[(x >> id) & 1] = new trie,
            child[(x >> id) & 1] -> v = 0;
        child[(x >> id) & 1] -> upd(id + u, lim, u, x, val);
        if(child[(x >> id) & 1] -> v == 0){
            delete child[(x >> id) & 1];
            child[(x >> id) & 1] = nullptr;
        }
        v += val;
    }

};

const int N = 5e4 + 3;
int n, m;
vector<int> adj[N];
int par[N];
char t;
int x, ans;
trie began;

void Enter(){
    cin >> m;
    began.child[1] = began.child[0] = nullptr;
    began.upd(30, -1, -1, 0, 1);
}

void check(trie &a, int id, int lim, int upd, int x){
    if(id == lim)
        return;
    if(a.child[!((x >> id) & 1)] != nullptr){
        ans |= 1 << id;
        check(*a.child[!((x >> id) & 1)], id + upd, lim, upd, x);
    }
    else
        check(*a.child[(x >> id) & 1], id + upd, lim, upd, x);
}

void solve(){
    while(m--){
        cin >> t >> x;
        if(t == '+')
            began.upd(30, -1, -1, x, 1);
        else if(t == '-')
            began.upd(30, -1, -1, x, -1);
        else{
            ans = 0;
            check(began, 30, -1, -1, x);
            cout << ans << "\n";
        }
    }
}

main(){
    fastIOfileinput();
    if(typetest){
        int t;
        cin >> t;
        while(t--){
            Enter();
            solve();
        }
    }
    else{
        Enter();
        solve();
    }
}