import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt(), m = scanner.nextInt();
        int[] shoot = new int[n];
        for (int i = 0; i < n; i++) {
            shoot[i] = scanner.nextInt();
        }
        int[] map = new int[m+1];
        int min = -1, cnt = 0;
        int l = 0, r = 0;
        for (; r < n; r++) {
            if (cnt == m) {
                for (; l <= r && cnt == m; l++) {
                    if (min == -1 || r-l < min) {
                        min = r - l;
                    }
                    int c = shoot[l];
                    if (c != 0) {
                        map[c]--;
                        if (map[c] == 0) {
                            cnt--;
                        }
                    }
                }
            }
            int c = shoot[r];
            if (c != 0) {
                if (map[c] == 0) {
                    cnt++;
                }
                map[c]++;
            }
        }
        if (cnt == m && (min == -1 || r-l < min)) {
            min = r - l;
        }
        System.out.println(min);
        scanner.close();
    }
}