int DeleteOdds( Node **a ) {
    if ( empty( *a ) ) return 0;
    while ( *a != NULL && (*a)->data % 2 == 1 ) *a = (*a)->next;
    Node *x = *a; Node *p;
    while ( x != NULL ) {
        bool flag = false;
        while ( x != NULL && x->data % 2 == 1 ) {
            Node *tmp = x;
            p->next = x->next;
            x = x->next;
            free( tmp );
            flag = true;
        }
        if ( x != NULL ) {
            p = x;
            x = x->next;
        }
    }
    return 0;
}