Scanner in = new Scanner(System.in);
            Deque<Integer> deque = new ArrayDeque<>();
            
            int n = in.nextInt();
            int m = in.nextInt();
            int max = 0;
            for (int i = 0; i < n; i++) {
                int num = in.nextInt();
                deque.add(num);
                if(deque.size()==m){
                    int size = new HashSet<Integer>(deque).size();
                    if(max<size) max = size;
                    deque.removeFirst();
                }
            }
            in.close();
            System.out.println(max);