import java.util.ArrayDeque;
import java.util.Deque;
import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

public class Solution {

    public static void main(String[] args) {
		Deque<String> deque = new ArrayDeque<>();
		Scanner sc = new Scanner(System.in);
		String input = sc.nextLine();
		String[] str = input.split(" ");
		int size = Integer.valueOf(str[0]);
		String s = sc.nextLine();
		sc.close();
		String[] s2 = s.split(" ");
		Set<String> set = new HashSet<>();
		int max = 0;
		for (int str1 = 0; str1 < Integer.valueOf(str[1]); str1++) {
			deque.offerLast(s2[str1]);
		}
		set.addAll(deque);
		max = set.size();
		
		for (int i = Integer.valueOf(str[1]) + 1; i < size; i++) {
			deque.pollFirst();
			deque.offerLast(s2[i]);
			set.clear();
			set.addAll(deque);
			max = Math.max(max, set.size());
		}
		
		System.out.println(max);
	}
}