// https://www.hackerrank.com/challenges/java-dequeue

import java.util.HashMap;

import java.util.Map;

import java.util.Scanner;

public class JavaDeQueue {

private static final Scanner SCANNER = new Scanner(System.in);

public static void main(String[] args) {

int length = SCANNER.nextInt();

int subArraySize = SCANNER.nextInt();

int[] array = getArray(length);

Map<Integer, Integer> frequencies = getElementsOfFirstSubArray(array, subArraySize);

int maxUniqueElements = frequencies.size();

for (int index = 0 ; index < array.length - subArraySize ; index++) {

remove(frequencies, array[index]);

frequencies.put(array[index + subArraySize],

frequencies.getOrDefault(array[index + subArraySize], 0) + 1);

maxUniqueElements = Math.max(maxUniqueElements, frequencies.size());

}

System.out.println(maxUniqueElements);

}

private static void remove(Map<Integer, Integer> frequencies, int element) {

if (frequencies.containsKey(element)) {

if (frequencies.get(element) <= 1) {

frequencies.remove(element);

} else {

frequencies.put(element, frequencies.get(element) - 1);

}

}

}

private static int[] getArray(int length) {

int[] array = new int[length];

for (int index = 0 ; index < array.length ; index++) {

array[index] = SCANNER.nextInt();

}

return array;

}

private static Map<Integer, Integer> getElementsOfFirstSubArray(int[] array, int subArraySize) {

Map<Integer, Integer> frequencies = new HashMap<>();

for (int index = 0 ; index < subArraySize ; index++) {

frequencies.put(array[index], frequencies.getOrDefault(array[index], 0) + 1);

}

return frequencies;

}

}