class ListNode{

  private Data data;
  private ListNode next = null;

  ListNode(Data d){data = d;}

  ListNode(Data d, ListNode ln){
    data = d;
    next = ln;
  }

  void store(Data d){data = d;}
  void store(ListNode ln){next = ln;}

  Data getData(){return data;}
  ListNode getNext(){return next;}

  public String toString(){
    return data.toString();
  }

}