import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {


  public static void main(String[] args) throws IOException {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    int target = Integer.parseInt(br.readLine());

    int clap = 0;
    for (int i = 3; i <= target; i++) {
      String s = String.valueOf(i);
      for (int j = 0; j < s.length(); j++) {
        if (s.charAt(j) == '3' || s.charAt(j) == '6' || s.charAt(j) == '9') {
          clap += 1;
        }
      }
    }
    System.out.println(clap);
  }
}