#include<bits/stdc++.h>
using namespace std;  
inline int read()  
{  
    int x=0,f=1;
    char s=getchar();  
    while(s<'0'||s>'9')
        {
            if(s=='-')
                f=-1;
            s=getchar();
        }  
    while(s<='9'&&s>='0')
        {
            x=x*10+s-'0';
            s=getchar();
        }  
    return x*f;  
}  
int main()  
{  
    char ch[50];  
    scanf("%s",ch);  
    bool flag=true;  
    for(int i=1;i<strlen(ch);i++)  
        if(ch[i]!='9')
            flag=false;  
    if(flag)
        printf("%d\n",(strlen(ch)-1)*9+ch[0]-'0');
    else  
        printf("%d\n",(strlen(ch)-1)*9+ch[0]-'0'-1);  
    return 0;  
}  