Node mergeLists(Node headA, Node headB) { 
	Node head= new Node();
    Node headTemp= head;
    
    while(headA !=null || headB !=null)
        {
             if(headA.data<=headB.data && headA !=null 
                && headB !=null) 
                {
                head.next=headA;
                headA=headA.next;
				}
			else if(headA.data>=headB.data &&headA !=null 
                    && headB !=null){
                head.next=headB;
                headB=headB.next;
				}
			else if(headA ==null){
					head.next=headB;
					headB=headB.next;
				}
			else if(headB ==null){
					head.next=headA;
					headA=headA.next;
				}
        head=head.next;
    }
    return headTemp.next;
	}