#include <bits/stdc++.h>
// #define int int64_t

#define FOR(i, a, b) for (int i = (a); i < int(b); ++i)
#define RFOR(i, a, b) for (int i = (b)-1; i >= int(a); --i)
#define rep(i, n) FOR(i, 0, n)
#define rep1(i, n) FOR(i, 1, int(n) + 1)
#define rrep(i, n) RFOR(i, 0, n)
#define rrep1(i, n) RFOR(i, 1, int(n) + 1)
#define all(c) begin(c), end(c)
namespace io {
#ifdef LOCAL
#define dump(...)                                         \
    do {                                                  \
        std::ostringstream os;                            \
        os << __LINE__ << ":\t" << #__VA_ARGS__ << " = "; \
        io::print_to(os, ", ", "\n", __VA_ARGS__);        \
        std::cerr << io::highlight(os.str());             \
    } while (0)
#define dump_(cntnr)                                 \
    do {                                             \
        std::ostringstream os;                       \
        os << __LINE__ << ":\t" << #cntnr << " = ["; \
        io::print_to_(os, ", ", "]\n", all(cntnr));  \
        std::cerr << io::highlight(os.str());        \
    } while (0)
#define dumpf(fmt, ...)                             \
    do {                                            \
        const int N = 4096;                         \
        auto b = new char[N];                       \
        int l = snprintf(b, N, "%d:\t", __LINE__);  \
        snprintf(b + l, N - l, fmt, ##__VA_ARGS__); \
        std::cerr << io::highlight(b) << std::endl; \
        delete[] b;                                 \
    } while (0)
#else
#define dump(...)
#define dump_(...)
#define dumpf(...)
#endif
std::string highlight(std::string s) {
#ifdef _MSC_VER
    return s;
#else
    return "\033[33m" + s + "\033[0m";
#endif
}
template <typename T>
void print_to(std::ostream &os, std::string, std::string tail, const T &first) {
    os << first << tail;
}
template <typename F, typename... R>
void print_to(std::ostream &os, std::string del, std::string tail, const F &first,
              const R &... rest) {
    os << first << del;
    print_to(os, del, tail, rest...);
}
template <typename I>
void print_to_(std::ostream &os, std::string del, std::string tail, I begin, I end) {
    for (I it = begin; it != end;) {
        os << *it;
        os << (++it != end ? del : tail);
    }
}
template <typename F, typename... R>
void println(const F &first, const R &... rest) {
    print_to(std::cout, "\n", "\n", first, rest...);
}
template <typename F, typename... R>
void print(const F &first, const R &... rest) {
    print_to(std::cout, " ", "\n", first, rest...);
}
template <typename I>
void println_(I begin, I end) {
    print_to_(std::cout, "\n", "\n", begin, end);
}
template <typename I>
void print_(I begin, I end) {
    print_to_(std::cout, " ", "\n", begin, end);
}
template <typename C>
void println_(const C &cntnr) {
    println_(std::begin(cntnr), std::end(cntnr));
}
template <typename C>
void print_(const C &cntnr) {
    print_(std::begin(cntnr), std::end(cntnr));
}
int _ = (
#ifndef LOCAL
    std::cin.tie(nullptr), std::ios::sync_with_stdio(false),
#endif
    std::cout.precision(10), std::cout.setf(std::ios::fixed));
}
using io::print;
using io::println;
using io::println_;
using io::print_;
template <typename T>
using vec = std::vector<T>;
using vi = vec<int>;
using vvi = vec<vi>;
using pii = std::pair<int, int>;
using ll = long long;
using ld = long double;
using namespace std;
// const int MOD = 1000000007;

const int ok = 0, eq = 1;

int solve(ll x) {
    string s = to_string(x);
    int n = s.size();
    ll dp[20][2] = {};
    dp[0][ok] = -100000;
    rep(i, n) {
        int d = s[i] - '0';
        dp[i+1][ok] = max(dp[i+1][ok], dp[i][ok] + 9);
        dp[i+1][eq] = max(dp[i+1][eq], dp[i][eq] + d);
        if (s[i] != '0') dp[i+1][ok] = max(dp[i+1][ok], dp[i][eq] + d - 1);
    }
    return max(dp[n][ok], dp[n][eq]);
}

int naive(const ll x) {
    ll ans = 0;
    rep(i, x + 1) {
        ll s = 0;
        ll y = i;
        while (y) s += y % 10, y /= 10;
        ans = max(ans, s);
    }
    return ans;
}

signed main() {
    ll x;

    // FOR(i, 1, 10000) {
    //     dump(i);
    //     int x, y;
    //     dump(x = solve(i), y = naive(i));
    //     assert(x == y);
    // }

    while (cin >> x) {
        print(solve(x));
    }
}


Measured memory_bytes: 256