struct Node {
  unique_ptr<Node> children[2];
  int count = 0;
  int value = -1;
};

void insert_number(Node *root, const int num, int add) {
  for (int i = 31; i >= 0; --i) {
    int idx = (bool)(num & (1 << i));
    if (!root->children[idx]) {
      root->children[idx].reset(new Node());
    }
    root->count += add;
    root = root->children[idx].get();
  }
  root->count += add;
  root->value = num;
}

int get_max_xor(Node *root, const int num, int level) {
  if (level < 0) {
    int v = root->value;
    assert(v != -1);
    int ret = num ^ v;
    return ret;
  }
  int bit = 1 - (bool)(num & (1 << level));
  if (root->children[bit] && root->children[bit]->count > 0) {
    return get_max_xor(root->children[bit].get(), num, level - 1);
  } else {
    return get_max_xor(root->children[1 - bit].get(), num, level - 1);
  }
}

void solve(const int n) {
  unique_ptr<Node> root(new Node());
  insert_number(root.get(), 0, +1);

  for (int i = 0; i < n; ++i) {
    char c; cin >> c;
    int num; cin >> num;
    if (c == '+') {
      insert_number(root.get(), num, +1);
    } else if (c == '-') {
      insert_number(root.get(), num, -1);
    } else {
      int ret = get_max_xor(root.get(), num, 31);
      cout << ret << "\n";
    }
  }

  cout.flush();
}