import java.util.Scanner; public class Main { private static int bingdu(String cur, int n) { if (cur.length() > 10 || Integer.parseInt(cur) > n) { return 0; } else { return 1 + bingdu(cur + "0", n) + bingdu(cur + "1", n); } } public static void main(String[] args) { Scanner scanner = new Scanner(System.in); while (scanner.hasNextInt()) { int n = scanner.nextInt(); System.out.println(bingdu("1", n)); } scanner.close(); } }