import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Scanner;
public class Main {
	public static void main(String[] args) throws Exception {
		PrintWriter pw=new PrintWriter(System.out);
		Scanner sc=new Scanner(System.in);

		int k=sc.nextInt();
		int n=sc.nextInt();

		int s=k;
		int t=k;
		int len=0;

		ArrayList<Integer> isPrime=new ArrayList<>();
		isPrime=PrimeList(n);
		int i=0;
		while(i<isPrime.size()&&isPrime.get(i)<k){
			i++;
		}
		int memP=k;
		for(;i<=n;i++){
			boolean[] used=new boolean[10];
			for(int j=i;j<isPrime.size();j++){
				int h=hash(isPrime.get(j));
				if(used[h])break;
				used[h]=true;
				if(j-i+1>=len){
					len=j-i+1;
					memP=isPrime.get(i);
				}
			}
		}


		pw.println(memP);
		pw.close();
		sc.close();
	} 

	public static boolean[] isPrime(int max){//trueでPrime
		boolean[] p=new boolean[max+1];
		Arrays.fill(p, true);
		p[0]=false;
		p[1]=false;
		for(int i=2;i<=max;i++){
			if(p[i]==true){
				for(int j=2;j*i<=max;j++){
					p[j*i]=false;
				}
			}
		}
		return p;
	}

	public static int hash(int n){
		int sum=0;
		while(n>=1){
			sum+=n%10;
			n=(n-n%10)/10;
		}
		n=sum;
		if(n>=10){
			return hash(n);
		}else{
			return n;	
		}
	}
	public static ArrayList<Integer> PrimeList(int max){
		ArrayList<Integer> isPrime=new ArrayList<>();
		boolean[] p=new boolean[max+1];
		p=isPrime(max);
		for(int i=2;i<=max;i++){
			if(p[i]){
				isPrime.add(i);
			}
		}
		return isPrime;
	}

}