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.
/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */


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

/**
 *
 * @author sousnake
 */
public class Headecimal_num {
    public static void main(String args[]) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(br.readLine());
        String sn  = Integer.toString(n);
        int k = sn.length();
        if(k==1){
            System.out.println(1);
            return;
        }
        String ns="";
        for(int i=0;i<k;i++){
            if(Integer.parseInt(sn.charAt(i)+"")>1){
                if(i!=0)
                    ns = sn.substring(0, i);
                for(int j=i;j<k;j++){
                    ns = ns+1;
                }
                break;
            }
            else if(Integer.parseInt(sn.charAt(i)+"")==1){
                ns=ns+1;
            }
            else if(Integer.parseInt(sn.charAt(i)+"")==0)
                ns=ns+0;
        }
        int j=Integer.parseInt(ns, 2);
        System.out.println(j);
    }
}
