void removeAllX(node*& pH, int x) {
    if (pH == nullptr) return;

    while (pH != nullptr && pH->data == x) {
        node* cur = pH;
        pH = pH->next;
        delete cur;
    }

    node* cur = pH;
    while (cur != nullptr && cur->next != nullptr) {
        if (cur->next->data == x) {
            node* temp = cur->next;
            cur->next = cur->next->next;
            delete temp;
        }
        else {
            cur = cur->next;
        }
    }
}