#include <bits/stdc++.h>

using namespace std;

#define INF 2000000000
#define x 1000000001
typedef long long ll;
typedef pair<int, int> P;


int main()
{
	ll n;
	cin >> n;
	string s = to_string(n);
	string org = s;
	int size = s.size();
	if (size<10) {
		cout << 0 << "\n";
		return 0;
	}
	int ret = 0;
	ret += (size - 10)*9;
	ret += (s[0]-'0')-1;
	int num = s[0]-'0';
	int tmp = size-9;
	for (int i = 0; i < tmp; i++) {
		s[i]=s[0];
		s[size-1-i]=s[0];
//		cout << s[i] << " " << s[size-1-i] << "\n";
	}
	ll tmp2 = stoll( s.c_str() );
	if (n>=tmp2) {
		ret++;
	}

	cout << ret << endl;

}