void xoa_pt_k(NodePtr &List,DataType x) 

{ 

    NodePtr p,q;

        for(int i=dem(List,x);i>1;i--) 

    { 

            p=timkiem(List,x);            

            if(p==List) 

                xoa_dau(List); 

            else 

            { 

                q=List; 

                while(q->Next !=p) 

                    q=q->Next; 

                q->Next=p->Next; 

                p->Next=NULL; 

                delete p; 

            }

    }

}