import java.util.Scanner;
import java.util.Arrays;
public class Main{
	public static void getPrimeArr(int arr[]) {
		  for(int i=0;i<arr.length;i++) {
			  boolean pd=true;
			  if(arr[i]%2==0)
				  continue;
			  for(int j=2;j<=Math.sqrt(arr[i]);j++)
    			     if(arr[i]%j==0) {
    				    pd=false;
    				    break;
    			     }
			  if(pd) 
				  System.out.println(arr[i]);
		  }
	}
	public static int [] getHuiWenArr(int a,int b) {
		  int brr[]=new int [b-a+1];
		  int n=0;
		  for(int i=a;i<=b;i++) {
			  int temp=i,ans=0;
			     while (temp!=0) {
			        ans=ans*10+temp%10;
			        temp/=10;
			     }
			  if(i==ans) {
				  brr[n]=i;
				  n++;
			  }
		  }
		  int count=0;
		  for(int i=0;i<brr.length;i++){
			  count++;
			  if(brr[i]==0)
				  break;
		  }
		  int crr[]=Arrays.copyOf(brr, count-1);
		  return crr;
	}
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String s=sc.nextLine();
		String [] strArr=s.split(" ");
		int arr[]=new int [2];
		for(int i=0;i<2;i++)
			arr[i]=Integer.parseInt(strArr[i]);
		getPrimeArr(getHuiWenArr(arr[0],arr[1]));
	}
}