struct Lista *InsertOrd(struct Lista *head, const char *data) {
    struct Lista *newp;
    struct Lista *tmp;
    char *new_data;

    /* aloca o novo item */
    newp = ((struct Lista*)malloc(sizeof(struct Lista)));
    new_data = strdup(data);
    //strdup aloca memória na pilha.
    if (newp == NULL || new_data == NULL) {
        fprintf(stderr, "out of memory");
        return NULL;
    }
    newp->data = new_data;
    newp->next = NULL;
    newp->prev=NULL;
    /* check if element should be inserted at the head */
    if (head == NULL || strcmp(new_data, head->data) < 0) {
        newp->next = head;
        newp->prev=head;
        head = newp;
    } else {
        /* otherwise find the point of insertion */
        tmp = head;
        while (tmp->next && strcmp(new_data, tmp->next->data) >= 0) {
            tmp = tmp->next;
        }
        newp->next = tmp->next;
        tmp->next = newp;
        newp->prev=tmp;
    }
    return head;
}