import java.util.Scanner;

public class Main {
   public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int a = scanner.nextInt();
        int b = scanner.nextInt();
        if(b > 100000000){
            b = 100000000;
        }
        if(a < 5){
            a = 5;
        }
        if(a % 2 == 0){
            a--;
        }
        for (int i = a; i <= b; i+=2) {
            if(i == 11){
                System.out.println(i);
                continue;
            }else if((i + "").length() % 2 == 0 || !fun2(i) || !fun1(i)){
                continue;
            }
            System.out.println(i);
        }
    }

    //判断质数
    public static boolean fun1(int num){
        for (int i = 2; i <= Math.sqrt(num); i++) {
            if(num % i == 0){
                return false;
            }
        }
        return true;
    }

    //判断回文数
    public static boolean fun2(int num){
        if(num < 10){
            return true;
        }
        char[] arr = (num + "").toCharArray();
        boolean a = true;
        for (int i = 0; i < arr.length; i++) {
            if(arr[arr.length - 1 - i] != (arr[i])){
                a = false;
                break;
            }
        }
        return a;
    }
}