C :

#include<stdio.h>
int huiWen(int x)
{
	int h=0,t=x;

	while(x>0){
		h=h*10+x%10;
		x/=10;
	}
	if(h==t){
		return 1;
	}else{
		return 0;
	}
}
int main()
{
	int n,i,c=0;
	scanf("%d",&n);
	for(i=1;i<=n;i++){
		if(huiWen(i)){
			c++;
		}
	}
	printf("%d",c);
	return 0;
}

C++ :

#include <iostream>
#include <cmath>

using namespace std;
bool sushu(int n){
	int i;
	bool f=true;
	for(i=2;i<=sqrt(n);i++){
		if(n%i==0){
			f=false;
			break;
		}
	}
	if(n<=1){
		f=false;
	}
	return f;
}
bool huiwen(int n){
	bool f=false;
	int g=n%10,s=n/10%10,b=n/100%10,q=n/1000%10,w=n/10000;
	if(n<=99&&g==s||n<=9){
		f=true;
	}
	else if(n>99&&n<=999&&g==b){
		f=true;
	}
	else if(n>999&&n<=9999&&g==q&&s==b){
		f=true;
	}
	else if(n>=10000&&g==w&&s==q){
		f=true;
	}
	return f;
	
}
int main(){
	int n,i,c=0;
	cin>>n;
	for(i=1;i<=n;i++){
		if(huiwen(i)==true){
			c++;
		}
	}
	cout<<c<<endl;
}

Pascal :

var a,b,c,d,e,f,g,huiwen:longint;s:string;

begin

  read(a);

  for b:=1 to a do

  begin

  str(b,s);

  d:=length(s);

  if d=1

  then inc(huiwen);

  if d=2

  then if s[1]=s[2]

       then inc(huiwen);

  if d=3

  then if s[1]=s[3]

       then inc(huiwen);

  if d=4

  then if (s[1]=s[4]) and (s[2]=s[3])

       then inc(huiwen);

end;

  write(huiwen);

end.

Java :

import java.util.Scanner;

public class Main{
	public static void main(String[] args) {
		int n=new Scanner(System.in).nextInt();
		int count=0;
		for(int i=1;i<=n;i++){
			if(isHws(i)){
				count++;
			}
		}
		System.out.println(count);
	}
	public static boolean isHws(int n){
		boolean f=true;
		char[] charArray=String.valueOf(n).toCharArray();	
			for(int i=0;i<charArray.length;i++){
				if(charArray[i]!=charArray[charArray.length-i-1]&&i!=charArray.length-i-1){
					f=false;break;
				}				
			}		
		return f;
	}
}

Python :

def dcf(x):
    a = []
    while x > 0:
        s = x % 10
        x //= 10
        a.insert(0, s)
    return a


n = int(input())
l = []
s = 0
c = 0

for i in range(10, n + 1):
    l = dcf(i)
    s = len(l)
    if s == 2 and l[0] == l[1]:
        c += 1
    elif s == 3 and l[0] == l[2]:
        c += 1
    elif s == 4 and l[0] == l[3] and l[1] == l[2]:
        c += 1
print(c + 9)