import java.util.*;

public class Solution { public static void main(String[] args) { Scanner scanner = new Scanner(System.in);

    int numberElements = scanner.nextInt();       // Declare and initialize
    int numberSubgroups = scanner.nextInt();      // Declare and initialize

    Deque<Integer> elementsWindow = new ArrayDeque<>(numberSubgroups); // Declare and initialize
    int maxUniqueValues = 1;
    HashMap<Integer, Integer> frequency = new HashMap<>(numberElements); // Declare and initialize

    for (int i = 0; i < numberElements; i++) {
        int element = scanner.nextInt();
        elementsWindow.addLast(element);

        if (!frequency.containsKey(element)) {
            frequency.put(element, 1);
        } else {
            frequency.put(element, frequency.get(element) + 1);
        }

        if (elementsWindow.size() == numberSubgroups) {
            int numInFrequency = 0;
            for (int value : frequency.values()) {
                if (value > 0) {
                    numInFrequency++;
                }
            }
            maxUniqueValues = Math.max(maxUniqueValues, numInFrequency);

            Integer elementRemoved = elementsWindow.removeFirst();
            int updatedCount = frequency.get(elementRemoved) - 1;
            if (updatedCount == 0) {
                frequency.remove(elementRemoved);
            } else {
                frequency.put(elementRemoved, updatedCount);
            }
        }
    }

    System.out.println(maxUniqueValues);
    scanner.close();
}

}