#include<bits/stdc++.h>
#define int long long
#define fr first
#define sc second
using namespace std;
int const N=1e6+5;
typedef pair<int,int> pii;
int n,m,sum,cnt,t,ans;
signed main()
{
//	freopen(".in","r",stdin);
//	freopen(".out","w",stdout);
	ios::sync_with_stdio(0);
	cin.tie(0),cout.tie(0);
    string s;
    cin>>s;
    int n=s.size();
    int p=(s[0]-'0');
    int w=s[n-1]-'0';
    n-=10;
    ans+=n*9;
    ans+=p;
    if(w<p)    ans--;
    cout<<ans<<'\n';
	return 0;
}