#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main()
{
    string s;
    cin >> s;
    bool van = false;
    long long muvdb = 0;
    for (int i = s.length()-1; i >= 0; i--)
    {
        if (!van && s[i] - '0' != 0 && i != 0) {
            van = true;
        }
        muvdb += s[i] - '0';
    }
    if (!van) {
        muvdb = s[0] - '0' + 9 * (s.length() - 1);
    }
    long long ossz = 0;
    for (int i = 1; i <= s.length() - 1; i++) {
        ossz += i;
    }
    cout << muvdb + 9 * ossz;
}

// 999 >> 991 >> 199 >> 190 >> 109 >> 100 >> 99