import java.util.Scanner;
public class 回文质数 {

	public static void main(String[] args) {
		Scanner input = new Scanner(System.in);
		long n = input.nextLong();
		long m = input.nextLong();
		for(long i = n;i<=m;i++) {
			if(iszhishu(i)&&ishuiwen(i))
				System.out.println(i);
		}
	}
	public static boolean iszhishu(long a) {
		boolean flag = true;
		if(a<=1)
			flag = false;
		for(long i = 2;i<=Math.sqrt(a);i++) {
			if(a%i==0) {
				flag = false;
				break;
			}
		}
		return flag;
	}
	public static boolean ishuiwen(long n) {
		boolean flag = false;
		String s = n+"";
		StringBuffer buff = new StringBuffer(s);
		long m  = Long.parseLong(buff.reverse().toString());
		if(n==m)
			flag = true;
		return flag;
	}
}

后三个TLE，大佬们救救本蒟蒻ba