在

#include <bits/stdc++.h>
using namespace std;
int main(){
int n,cnt=0;
cin>>n;
if(n<=9){
cout<<n;
return 0;
}else if(n<=99){
cnt=n/11+9;
}else if(n<=999){
cnt=n/111+18;
}else if(n<=2025){
cnt=n/1111+27;
}
cout<<cnt;
return 0;
}