#include <bits/stdc++.h>
#include<iostream>
#include<map>
#include<vector>
#include <algorithm>
#include<math.h>
#include <iomanip>
#include<set>
#include <numeric>
#include<string>
using ll = long long;
using namespace std;

int main()
{
    string n;
    ll ans = 0;
    cin >> n;
    if (n.size() < 3) cout << 0 << "\n";
    else if (n.size() >= 3 && (n.size()%3)){
        ans = pow(10, n.size()/3) - 1;
        cout << ans << endl;
    } else {
        string a, b, c;
        ans = pow(10, n.size()/3 - 1) - 1;
        a = n.substr(0, n.size()/3);
        b = n.substr(n.size()/3, n.size()/3);
        c = n.substr(n.size()*2/3, n.size()/3);
        if (stoll(a) != (ans+1)) ans += (stoll(a) - 1);
        if (stoll(a) < stoll(b)) ans++;
        else if ((stoll(a) == stoll(b)) && (stoll(a) <= stoll(c)))ans++;
        cout << ans << endl; 
    }
}