题解 | #自守数#

import java.util.*;
import java.io.*;
public class Main{
    public static void main(String[] args) throws IOException{
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        String s=null;
        while((s=br.readLine())!=null){
            //char[] chars=s.toCharArray();
            int n=Integer.valueOf(s);
            int count=0;
            for(int i=0;i<=n;i++){
                if(isZishoushu(i)!=-1){
                    count++;
                }
            }
            System.out.println(count);
        }
    }
    public static int isZishoushu(int b){
        int n=b;
        int power=n*n;
        int counts=0;
        while(n>0){
            n=n/10;
            counts++;
        }
        int flag=0;
        for(int i=0;i<counts;i++){
            if(power%10!=b%10){
                return -1;
            }
            b=b/10;
            power=power/10;
        }
        return n;
    }
}