#include<bits/stdc++.h>
using namespace std;
int main(){
    int a[28]={1,2,3,4,5,6,7,8,9,11,22,33,44,55,66,77,88,99,111,222,333,444,555,666,777,888,999,1111},n;
    cin>>n;
    for(int i=0;i<28;i++)
        if(a[i]>n){
            cout<<i;
            return 0;
        }
    cout<<28;
    return 0;
}