import java.util.Scanner;

public class Main1217 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int a = scanner.nextInt();
        int b = scanner.nextInt();
        for (int i = a; i <= b; i += 2) {
            int count = 0;
            for (int j = 3; j <= i ; j += 2) {
                if(i % j == 0){
                    count++;
                }
            }
            if(count == 1){
                String[] arr = (i + "").split("");
                boolean c = true;
                for (int j = 0; j < arr.length; j++) {
                    if(!arr[j].equals(arr[arr.length - 1 - j])){
                        c = false;
                        break;
                    }
                }
                if(c){
                    System.out.println(i);
                }
            }
        }
    }
}