#include<bits/stdc++.h>
#define rep(i,n)for(int i=0;i<(n);i++)
using namespace std;
typedef long long ll;
typedef pair<int, int>P;

int main() {
	ll a = 1e9 + 1;
	ll n; cin >> n;
	int cnt = 0;
	for (int i = 1; i < 9; i++) {
		for (int j = 1; j <= 9; j++) {
			string s; rep(k, i)s += j + '0';
			ll b = stoll(s);
			if (a*b > n)break;
			else cnt++;
		}
	}
	cout << cnt << endl;
}