#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < n; i++)
#define srep(i,a,b) for(int i = a; i < b; i++)
#define all(A) (A).begin(),(A).end()
#define MOD 1000000007
using namespace std;
using ll = long long;

struct Edge {
	ll to,cost;
};

using Graph = vector<vector<int>>;
using P = pair<int,int>;
const ll INF = 1LL<<60;

int main() {
	ll n; cin >> n;
	int ans = 0;
	rep(i,100001){
		string t = to_string(i+1);
		string s = t+t+t;
		if(n >= stoll(s)) ans++;
	}
	cout << ans;
}