#include <iostream>
#include <algorithm>
using namespace std;
typedef long long ll;
int main() {
	ll n;	cin >> n;
	ll base = 1e9 + 1;
	ll cnt = 0;
	ll multi = 1;
	ll num = 1;
	ll m = base;
	while (n >= m) {
		cnt++;
		num++;
		if (num == 10) {
			multi = multi * 10 + 1;
			num = 1;
		}
		m = base*num*multi;
	}
	cout << cnt << endl;
}