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

using namespace std;

const long long MOD = (long long)(1e9) + 7;

map<string , int> mp;
long long n;
int d;

void dfs(string s) {
  if (s.size() > d) {
    return;
  }

  if ((long long)stoi(s) > n) {
    return;
  }

  mp[s]++;
  dfs(s + "3");
  dfs(s + "6");
  dfs(s + "9");
  dfs(s + "0");

  return;
}

int main() {

  //cout << fixed << setprecision(15);

  cin >> n;
  d = to_string(n).size();
  
  for (int i = 12; i <= min(99LL , n); i += 3) {
    mp[to_string(i)]++;
  }

  dfs("3");
  dfs("6");
  dfs("9");

  cout << mp.size() - 3 << endl;

  return 0;
}