void MergeList_L(LinkList &La,LinkList &Lb,LinkList &Lc){
    pa=La->next;pb=Lb->next;
    Lc=pc=La;
    while(pa&&pb){
      if(pa->data<=pb->data){
         pc->next=pa;pc=pa;pa=pa->next;
      }
    else{pc->next=pb;pc=pb;pb=pb->next;}
    }
    pc-next=pa?pa:pb;
    free(Lb);
}//MergeList_L