#include <bits/stdc++.h>
using namespace std;

template <typename A, typename B>
string to_string(pair<A, B> p);

template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p);

template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p);

string to_string(const string& s)
{
    return '"' + s + '"';
}

string to_string(const char* s)
{
    return to_string((string)s);
}

string to_string(bool b)
{
    return (b ? "true" : "false");
}

string to_string(vector<bool> v)
{
    bool first = true;
    string res = "{";
    for (int i = 0; i < static_cast<int>(v.size()); i++) {
        if (!first) {
            res += ", ";
        }
        first = false;
        res += to_string(v[i]);
    }
    res += "}";
    return res;
}

template <size_t N>
string to_string(bitset<N> v)
{
    string res = "";
    for (size_t i = 0; i < N; i++) {
        res += static_cast<char>('0' + v[i]);
    }
    return res;
}

template <typename A>
string to_string(A v)
{
    bool first = true;
    string res = "{";
    for (const auto& x : v) {
        if (!first) {
            res += ", ";
        }
        first = false;
        res += to_string(x);
    }
    res += "}";
    return res;
}

template <typename A, typename B>
string to_string(pair<A, B> p)
{
    return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}

template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p)
{
    return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ")";
}

template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p)
{
    return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ", " + to_string(get<3>(p)) + ")";
}

void debug_out() { cerr << endl; }

template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T)
{
    cerr << " " << to_string(H);
    debug_out(T...);
}

#ifndef ONLINE_JUDGE
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif

// #define int long long

int dp[11][11][2];
int dpz[11][11][2][2];

int cal(const vector<int>& digit, int d)
{
    int n = digit.size();
    memset(dp, 0, sizeof(dp));

    dp[0][0][0] = 1;
    for (int i = 0; i < n; ++i) {
        for (int cnt = 0; cnt <= 10; ++cnt) {
            for (int lower = 0; lower < 2; ++lower) {
                if (dp[i][cnt][lower] == 0)
                    continue;
                for (int ndigit = 0; ndigit <= 9; ++ndigit) {
                    if (ndigit > digit[i] && lower == 0)
                        continue;
                    int nlower = lower || ndigit < digit[i];
                    int ncnt = cnt + (ndigit == d);

                    dp[i + 1][ncnt][nlower] = 1;
                }
            }
        }
    }

    int res = 0;
    for (int i = 0; i <= 10; ++i)
        if (dp[n][i][0] || dp[n][i][1])
            res = max(res, i);

    debug(d, res);
    return res;
}

int calz(const vector<int>& digit)
{
    int n = digit.size();
    memset(dp, 0, sizeof(dp));

    dpz[0][0][0][0] = 1;
    for (int i = 0; i < n; ++i) {
        for (int cnt = 0; cnt <= 10; ++cnt) {
            for (int lower = 0; lower < 2; ++lower) {
                for (int zero = 0; zero < 2; ++zero) {
                    if (dpz[i][cnt][lower][zero] == 0)
                        continue;
                    for (int ndigit = 0; ndigit <= 9; ++ndigit) {
                        if (ndigit > digit[i] && lower == 0)
                            continue;
                        int nlower = lower || ndigit < digit[i];
                        int ncnt = cnt + (ndigit == 0 && zero == 1);
                        int nzero = zero || (ndigit != 0);

                        dpz[i + 1][ncnt][nlower][nzero] = 1;
                    }
                }
            }
        }
    }

    int res = 1;
    for (int i = 0; i <= 10; ++i)
        if (dpz[n][i][0][1] || dpz[n][i][1][1])
            res = max(res, i);
    return res;
}
void solve()
{
    int n;
    cin >> n;

    vector<int> digit;
    while (n) {
        digit.push_back(n % 10);
        n /= 10;
    }

    reverse(digit.begin(), digit.end());
    int res = 0;

    for (int i = 1; i <= 9; ++i)
        res += cal(digit, i);

    res += calz(digit);
    cout << res << '\n';
}

signed main()
{

#ifndef ONLINE_JUDGE
    freopen("out.txt", "w", stdout);
    freopen("in.txt", "r", stdin);
#endif
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    int t = 1;
    // cin >> t;

    while (t--) {
        solve();
    }

    return 0;
}