题解 | #自守数#

import java.util.*;
public class Main {
        public static void main(String[] args){
            Scanner sc = new Scanner(System.in);
            while(sc.hasNext()){
                int n = sc.nextInt();
                int count = 0;
                for(int i=0;i<=n;i++){
                    int sum =i*i;
                    String s1 = String.valueOf(i);
                    String s2 = String.valueOf(sum);
                    //从平方的尾部往前截取到与当前数长度相同的子串
                    if(s2.substring(s2.length()-s1.length()).equals(s1)){
                        count++;
                    }
                }
                System.out.println(count);
            }
        }
}