#include <iostream>
#include <algorithm>
using namespace std;

using ll = long long;



int main(void){
    // Here your code !
    ll n;
    cin >> n;
    
    //1 - 9 , 11 , 22 , 33 , 99 , 111
    
    ll tmp = 1;
    ll res = 0;
    
    while(true){
        for(int i = 1; i <= 9; i++){
            if( (n) >= tmp * i * 1000000001 ){
                //cout << tmp * i << endl;
                res++;
            }else{
                cout << res << endl;
                return 0;
            }
        }
        tmp = tmp * 10 + 1;
    }
    
}