#include<bits/stdc++.h>
#include<sstream>
using namespace std;
int main()
{
    int n,s=0;
    cin>>n;
    for(int i=1;i<=n;i++)
    {
        int a=i,b=i%10;
        bool c=1;
        while(a!=0)
        {
            if(a%10!=b)c=0;
            a/=10;
        }
        if(c)s++;
    }
    cout<<s;
}

C++ :

#include <algorithm>
#include <cstdio>
using namespace std;
int n, ans;
int main() {
	scanf("%d", &n);
	for (int i = 1; i <= n; i++) {
	int v = i % 10, t = i / 10, chk = 1;
	while (t) {
		if (t % 10 != v) chk = 0;
			t /= 10;
		}
		ans += chk;
	}
	printf("%d\n", ans);
	return 0;
}