One beautiful July morning a terrible thing happened in Mainframe: a mean virus Megabyte somehow got access to the memory of his not less mean sister Hexadecimal. He loaded there a huge amount of n different natural numbers from 1 to n to obtain total control over her energy.

But his plan failed. The reason for this was very simple: Hexadecimal didn't perceive any information, apart from numbers written in binary format. This means that if a number in a decimal representation contained characters apart from 0 and 1, it was not stored in the memory. Now Megabyte wants to know, how many numbers were loaded successfully.

Input

Input data contains the only number n (1 ≤ n ≤ 109).

Output

Output the only number — answer to the problem.

Examples

Input

10


Output

2

Note

For n = 10 the answer includes numbers 1 and 10.
import java.io.BufferedReader;
import java.io.InputStreamReader;

public class ProblemC {
  public static void main(String[] args) throws Exception {
    BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
    String strBuff = reader.readLine().trim();
    byte[] chars = strBuff.getBytes("US-ASCII");
    StringBuffer binBuff = new StringBuffer();
    boolean only1 = false;
    for (int i = 0; i < chars.length; i++) {
        byte b = chars[i];
        if (only1) {
            binBuff.append('1');
        } else if (b > '1') {
            only1 = true;
            binBuff.append('1');
        } else if (b == '0' || b == '1') {
            binBuff.append((char) b);
        } else {
            throw new IllegalArgumentException("Input contains illegal characters!");
        }
    }
    System.out.println(Long.parseLong(binBuff.toString(), 2));
  }
}