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.
/*
 * @author rushikesh kavar
 */
import java.util.Scanner;
public class Solution {
    public static void main(String[] args) {
        int n;
        Scanner sc=new Scanner(System.in);
        n=sc.nextInt();
        solve(n);
    }
    private static void solve(int n){
        String t=Integer.toString(n);
        int i=0;
        char arr[]=new char[t.length()];
        while( i<t.length() && (t.charAt(i)=='0' || t.charAt(i)=='1')){
            arr[i]=t.charAt(i);
            i++;
        }
        for(int j=i;j<arr.length;j++) arr[j]='1';
        String answer="";
        for(i=0;i<arr.length;i++){
            answer=answer+arr[i];
        }
        System.out.println(Integer.valueOf(answer,2));
    }
        
    }
