static int findMergeNode(SinglyLinkedListNode head1, SinglyLinkedListNode head2) {

        HashMap<SinglyLinkedListNode, Integer> map = new HashMap<>();
        SinglyLinkedListNode temp1 = head1;
        SinglyLinkedListNode temp2 = head2;
        
        while(temp1 != null)
        {
                map.put(temp1, 1);
                temp1 = temp1.next;
            
        }
        while(temp2 != null)
        {
            if(map.containsKey(temp2))
            {
                return temp2.data;
            }
            else{
                map.put(temp2, 1);
                temp2 = temp2.next;
            }
        }
        return -1;
				
    }