public static LinkedListNode findloop(LinkedListNode n) {
		if(n==null || n.next == null)
			return null;
		
		LinkedListNode quick=n, slow=n;
		
		while(true) {
			if(quick == null || quick.next == null)
				return null;
			quick = quick.next.next;
			slow = slow.next;
			if(quick == slow)
				break;
		}
		
		quick = n;
		
		while(true) {
			if(quick == slow)
				return slow;
			quick = quick.next;
			slow = slow.next;
		}
	}