题解 | #自守数#

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner fzhinput = new Scanner(System.in);
        int sz = fzhinput.nextInt();
        int num = 0, dbz = 0;
        for (int i = 0; i <= sz; i++) {
            int z = i * i;
            if (i < 10) {
                dbz = z % 10;
            } else if (i < 100) {
                dbz = z % 100;
            } else if (i < 1000) {
                dbz = z % 1000;
            } else if (i < 10000) {
                dbz = z % 10000;
            } else if (i < 100000) {
                dbz = z % 100000;
            }
            if (i == dbz) {
                num++;
            } else {

            }
        }
        System.out.println(num);
    }
}