import java.util.*;
public class Main {
    public static boolean isPrime(int num) {
        if (num < 2) {
            return false;
        }
        for (int i = 2; i <= Math.sqrt(num); i++) {
            if (num % i == 0) {
                return false;
            }
        }
        return true;
    }
    public static boolean isPalindrome(int num) {
        int c = num;
        int d = 0;
        while (c > 0) {
            int m = c % 10;
            d = d * 10 + m;
            c /= 10;
        }
        return num == d;
    }
    public static void main(String[] args) {
        Scanner n = new Scanner(System.in);
        int a = n.nextInt(), b = n.nextInt();
        for (int i = a; i <= b; i++) {
            if (isPrime(i) && isPalindrome(i)) {
                System.out.println(i);
            }
        }
    }
}

不知道怎么改了