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

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int k = sc.nextInt();
        int n = sc.nextInt();
        boolean[] isNotPrime = new boolean[n + 1];
        HashSet<Integer> used = new HashSet<>();
        ArrayDeque<Integer> primes = new ArrayDeque<>();
        int max = 0;
        int maxIdx = 0;
        int left = k;
        for (int i = 2; i <= n; i++) {
            if (isNotPrime[i]) {
                continue;
            }
            for (int j = 2; j * i <= n; j++) {
                isNotPrime[j * i] = true;
            }
            if (i < k) {
                continue;
            }
            int hash = getHash(i);
            if (used.contains(hash)) {
                while (true) {
                    int remain = getHash(primes.poll());
                    if (hash == remain) {
                        break;
                    }
                    used.remove(remain);
                }
            }
            primes.add(i);
            used.add(hash);
            if (max <= primes.size()) {
                max = primes.size();
                maxIdx = primes.peek();
            }
        }
        System.out.println(maxIdx);
    }
    
    static int getHash(int x) {
        if (x < 10) {
            return x;
        } else {
            int sum = 0;
            while (x > 0) {
                sum += x % 10;
                x /= 10;
            }
            return getHash(sum);
        }
    }
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public String nextLine() throws Exception {
        return br.readLine();
    }
    
    public String next() throws Exception {
        if (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
}