[BOJ] 1747. 소수&팰린드롬

import java.util.Arrays;
import java.util.Scanner;

public class Main {
	static Scanner sc=new Scanner(System.in);
	static int N=sc.nextInt();
	static int arr[];
	static boolean notPrime[]=new boolean[1003002];
	public static void main(String[] args) {
		for (int i = 1; i <= 1003001; i++) {
			for (int j = 2; j*j <= i; j++) {
				if(i%j==0) {
					notPrime[i]=true;
					break;
				}
			}
		}
		notPrime[1]=true;

		for (int i = N; i <= 1003001; i++) {
			if(!notPrime[i] && isPel(intToArr(i))) {
				System.out.println(i);
				break;
			}
		}
	}
	public static boolean isPel(int arr[]) {
		for (int i = 0; i < arr.length/2; i++) {
			if(arr[i]!=arr[arr.length-1-i]) {
				return false;
			}
		}
		return true;
	}
	
	public static int[] intToArr(int num) {
		int s=size(num);
		arr=new int[s];
		int cnt=s;
		while(num/10!=0) {
			arr[--cnt]=num%10;
			num=num/10;
		}
		arr[--cnt]=num%10;
		return arr;
	}
	
	public static int size(int num) {
		int cnt=1;
		while(num/10!=0) {
			cnt++;
			num=num/10;
		}
		return cnt;
	}
}