C

#include <algorithm>
#include <iostream>
#include <array>
#include <vector>
#include <numeric>
#include <random>
#include <chrono>
#include <set>
#include <cassert>
#include <bitset>


using namespace std;

#define int long long
#pragma comment(linker,"/STACK:1000000000,1000000000")

const long long INF = 1e9 + 7;
const int MAXN = 2e5 * 32 + 100;
const int N = 1e5 + 10;

struct vertex {
    int next[3];
    int terminal = 0;
} v[MAXN];

array<int, MAXN> kol;

int root = 0, top = 1;

inline void add(int num) {
    int cur = root;
    bitset<32> a(num);
    for (int i = 31; i >= 0; --i) {
        if (v[cur].next[a[i]] == 0) {
            v[cur].next[a[i]] = top++;
        }
        ++kol[cur];
        cur = v[cur].next[a[i]];
    }
    ++kol[cur];
    v[cur].terminal = num;
}

inline void del(int num) {
    int cur = root;
    bitset<32> a(num);
    for (int i = 31; i >= 0; --i) {
        --kol[cur];
        cur = v[cur].next[a[i]];
    }
    --kol[cur];
    v[cur].terminal = 0;
}

inline int get(int num) {
    int cur = root;
    bitset<32> a(num);
    int res = 0;
    for (int i = 31; i >= 0; --i) {
        if (v[cur].next[!a[i]] != 0 && kol[v[cur].next[!a[i]]]) {
            cur = v[cur].next[!a[i]];
            res |= 1 << i;
        } else {
            cur = v[cur].next[a[i]];
        }
    }
    return res;
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);

    add(0);

    int q;
    cin >> q;
    while (q--) {
        char type;
        int x;
        cin >> type >> x;
        if (type == '+') {
            add(x);
        } else if (type == '-') {
            del(x);
        } else if (type == '?') {
            cout << get(x) << '\n';
        }
    }
}