const int MAX = 2e5 * 32;
vector<node> t(MAX);
int leaf = 1;

string bin(int &num) {
    string res;
    while (num) {
        res += '0' + (num & 1);
        num >>= 1;
    }
    reverse(all(res));
    int k = 30 - res.size();
    string zeroes;
    for (int i = 0; i < k; ++i) zeroes += '0';
    return zeroes + res;
}

int unbin(string &num) {
    int res = 0; int deg = (1 << (int)(num.size()) - 1);
    for (auto el : num) {
        int k = el - '0';
        res += k * deg;
        deg >>= 1;
    }
    return res;
}

void add(int &num) {
    int v = 0;
    string bin_num = bin(num);
    for (auto el : bin_num) {
        int k = el - '0';
        if (t[v].next[k] == 0) {
            t[v].next[k] = leaf++;
        }
        v = t[v].next[k]; t[v].cnt++;
    }
}

void del(int &num) {
    int v = 0;
    string bin_num = bin(num);
    for (auto el : bin_num) {
        v = t[v].next[el - '0'];
        t[v].cnt--;
    }
}

void get(int &num) {
    int v = 0;
    int num1 = num;
    string bin_num = bin(num1);
    string ans;
    for (auto el : bin_num) {
        int k = el - '0';
        if (t[t[v].next[1 - k]].cnt) {
            v = t[v].next[1 - k];
            ans += (1 - k) + '0';
        } else {
            v = t[v].next[k];
            ans += el;
        }
    }
    cout << (unbin(ans) ^ num) << '\n';
}

int main() {
    int q;
    cin >> q;
    char type; int x;
    while (q--) {
        cin >> type >> x;
        if (type == '+') {
            add(x);
        } else if (type == '-') {
            del(x);
        } else {
            get(x);
        }
    }
    return 0;
}