public boolean add(Object Data) 
    {
        Node a = new Node();
        a.data = Data;
        if(this.length==0)
        {
            this.head = a;
            this.tail = this.head;
            this.head.next = null;
        }
        else
        {
            Node p = this.head;
            while(p.next!=null)
            {
                if(p.data<=a.data)
                {
                    a.next = p.next;
                    p.next = a;
                }
            }
        }
        return false;
    }