蒟蒻求助！

最后一个样例老是tle 哭

import java.io.BufferedInputStream;
import java.io.BufferedWriter;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.Scanner;

public class Main {
    static int a,b;
    static PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
    static boolean is_Reverse(int num){
        String str = num + "";
        char[] c = str.toCharArray();
        for(int i = str.length() - 1;i >= 0;i --)
            if(str.charAt(i) != c[str.length() - 1 - i])
                return false;
        return true;
    }
    static boolean is_zs(int num){
        if(num == 2)
            return true;
        for(int i = 2;i <= Math.sqrt(num);i ++)
            if(num % i == 0)
                return false;
        return true;
    }
    public static void main(String[] args){
        Scanner sc = new Scanner(new BufferedInputStream(System.in));
        a = sc.nextInt();
        b = sc.nextInt();
        if(a == 1 || a == 2) {
            out.println(2);
            a = 3;
        }
        for(int i = a;i <= b;i ++){
            if(is_Reverse(i) && is_zs(i)){
                out.println(i);
            }
        }
        out.flush();
        out.close();
    }
}