2018校招 回文素数

import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;

public class Main {
public static boolean huiwen(int n){
String string=String.valueOf(n);
StringBuilder stringBuilder=new StringBuilder(string);
String string2=stringBuilder.reverse().toString();
for (int i = 0; i < string.length(); i++) {
if (string.charAt(i)!=string2.charAt(i)) {
return false;
}
}
return true;
}
public static void main(String[] args) {
Scanner scanner=new Scanner(System.in);
String string;
boolean flag[]=new boolean[1020];
int prime[]=new int[1020];
int count=0;
for (int i = 2; i < prime.length; i++) {
if (!flag[i]) {
prime[count++]=i;
for (int j = i; j < prime.length; j+=i) {
flag[j]=true;
}
}
}
int l=scanner.nextInt();
int r=scanner.nextInt();
int sum=0;
for (int i = 0; i <count; i++) {
if (prime[i]>=l&&prime[i]<=r&&huiwen(prime[i])) {
sum++;
}
}
System.out.println(sum);
}
}