public static void removeLoop(Node head){
        // code here
        // remove the loop without losing any nodes
        HashSet<Node> hs=new HashSet<Node>();
        
        while(head!=null)
        {
            hs.add(head);
            if(hs.contains(head.next))
            {
                head.next=null;
                break;
            }
            head=head.next;
        }
    }