C++ :

#include <bits/stdc++.h>
using namespace std;

int i,n,c = 0;
int main() {
	 cin>>n;
	 for(i = 1;i <= n;i++){
	 	if(i*i%10==i||i*i%100==i||i*i%1000==i||i*i%10000==i||i*i%100000==i||i*i%1000000==i){
	 		c++;
	 		//cout<<i<<endl;
		 }
	 }
	 
	 cout<<c;
}

Java :

import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int s = 0 ; 
		for(int i = 1 ; i <= n ; i++)
		{
			if((i*i)%10 == i || (i*i)%100 == i || (i*i)%1000 == i || (i*i)%10000 == i ||(i*i)%100000 == i)
			{
				s++;
			}
		}
		System.out.println(s);
  	}
 }

Python :

# 接收输入：思路是转换为字符串来处理
n = int(input())
c = 0
for i in range(1, n + 1):
    # 平方的结果转成字符串
    a = str(i * i)
    # 把i转化成字符串
    b = str(i)
    # 得到i字符串的位数
    t = len(b)
    if a[t*(-1):] == b:
        c += 1
print(c)