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

#define int long long
#define double long double

#define pii pair<int, int>

signed main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
#ifdef CB
	freopen("be2.txt", "r", stdin);
//	freopen("out.txt", "w", stdout);
#endif
	string S;
	cin >> S;
	int ans = 0;
	if (count(S.begin(), S.end(), '0') == S.size() - 1) {
		if (S[0] == '1') {
			ans++;
		}
		else {
			ans += S[0] - '0' + 9 * (S.size() - 1);
		}
	}
	else {
		for (char c : S) {
			ans += c - '0';
		}
	}
	for (int i = (int)S.size() - 1; i > 0; i--) {
		ans += 9 * i;
	}
	cout << ans << '\n';
	return 0;
}