import java.io.*;
import java.util.*;

public class Main {

    public static void main(String[] args) throws Exception {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        int K = Integer.parseInt(br.readLine());
        int N = Integer.parseInt(br.readLine());

        int sc = (int) Math.sqrt(N);

        int[] d = new int[N + 1];

        d[0] = 1;
        d[1] = 1;

        for (int i = 2; i <= sc; i++) {
            if (d[i] != 0) {
                continue;
            }
            for (int j = i; j < N; j++) {
                int dest = i * j;
                if (dest > d.length - 1) {
                    break;
                }
                d[i * j] = 1;
            }
        }

        int tmpMax = Integer.MIN_VALUE;
        int min = Integer.MAX_VALUE;

        int diff = Integer.MIN_VALUE;

        for (int i = K; i <= N; i++) {
            if (d[i] == 1) {
                continue;
            }

            if (d[i] == 0) {
                d[i] = change(i);
            }
            int tmp = d[i];

            int j = i + 1;

            HashMap<Integer, Integer> map = new HashMap();
            map.put(d[i], i);
            for (; j <= N; j++) {
                if (d[j] == 1) {
                    continue;
                } else if (d[j] == 0) {
                    d[j] = change(j);
                }

                if (map.containsKey(d[j])) {
                    break;
                } else {
                    tmpMax = j;
                    map.put(d[j], j);
                }
            }

            if (diff <= tmpMax - i) {
                diff = tmpMax - i;
                min = i;
            }
        }

        System.out.println(min);
    }

    private static int change(int source) {
        char[] c = Integer.toString(source).toCharArray();
        while (c.length != 1) {

            source = 0;
            if (c.length > 1) {
                for (int i = 0; i < c.length; i++) {
                    source += Integer.parseInt(String.valueOf(c[i]));
                }
            } else {
                source += Integer.parseInt(String.valueOf(c));
                break;
            }

            c = Integer.toString(source).toCharArray();
        }

        return source;
    }
}