SinglyLinkedListNode* removeNodes(SinglyLinkedListNode* listHead, int x) {
    SinglyLinkedListNode* tmp = listHead;
    int init_case = 0;
    // initial first item
    if (tmp->data <= x){
        tmp = tmp->next;
    }
    else {
        SinglyLinkedListNode* removethis = tmp;
        tmp->next = tmp->next->next;
        delete removethis;
        init_case = 1;
    }

    while (tmp->next != NULL){

        if ( tmp->next->data <= x){
            // tmp->next->data <= x; continue traversing the list
            tmp = tmp->next;
        }
        else {
            // tmp->next->data < x; remove node
            SinglyLinkedListNode* removethis = tmp->next;
            tmp->next = tmp->next->next;
            delete removethis;
        }
    }

    if (init_case){
        return listHead->next;
    }

    else{
        return listHead;
    }
}