#include <iostream>
#include <vector>
#include <algorithm>
#include <functional>
#include <queue>
#include <map>
#include <cmath>
#include <iomanip>
#include <set>
#include <cstdio>
#include <string>

using namespace std;

int main() {
  int n;
  cin >> n;
  map<long long, int> mp;
  for (int i = 1; i < 1000000; i++) {
    if (i >= n) break;
    string s = to_string(i) + to_string(i) + to_string(i);
    long long now = stoll(s);
    if (now <= n) {
      mp[now]++;
    }
  }
  cout << mp.size() << endl;
  return 0;
}