#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define loop(i,a,b) for(i=a;i<b;i++)
#define rloop(i,a,b) for(i=a;i>=b;i--)
#define vi vector<int>
#define vl vector<ll>
#define vii vector< vector<int> >
#define vll vector< vector<ll> >
#define vs vector<string>
const int inf=1000000001;
const ll INF=1e16;
#define MOD 1000000007
#define mod 1000000009
#define pi 3.14159265358979323846

int main(){
	string n;
	int i;
	cin>>n;
	if(n.size()==19){
		n="999999999999999999";
	}else if(n.size()<=9){
		cout<<0<<endl;
		return 0;
	}
	int ans=0;
	ans+=(n.size()-10)*9;
	string s;
	char k=n[0];
	loop(i,0,n.size()-9){
		s.push_back(k);
	}
	loop(i,0,18-n.size()){
		s.push_back('0');
	}
	loop(i,0,n.size()-9){
		s.push_back(k);
	}
	if(n<s){
		ans+=k-'0'-1;
	}else{
		ans+=k-'0';
	}
	cout<<ans<<endl;
}