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.util.ArrayList;
import java.util.Scanner;

public class P9C {
    
    ArrayList<String> bin = new ArrayList<String>();
    
    P9C (){
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        sc.close();
        

        ArrayList<String> current = new ArrayList<String>();
        current.add("0");
        current.add("1");
        for (int i = 1; i < 10; i++){
            for (int j = 0; j < current.size(); j++){
                if (!current.get(j).startsWith("0")){
                    bin.add(current.get(j));
                }
            }
            current = binaryN(current);
        }
        bin.add("1000000000");
        
        if (bin.contains(n +"")){
            System.out.println(bin.indexOf(n+"") + 1);
        }
        else {
            int i = 0;
            for (; i < bin.size(); i++){
                if (Long.parseLong(bin.get(i)) > n){
                    System.out.println(i);
                    break;
                }
            }
            
        }
    }
    
    ArrayList<String> binaryN(ArrayList <String> bin1){
        ArrayList<String>current = new ArrayList<String>();
        for (int i = 0; i < bin1.size(); i++){
            current.add("0" + bin1.get(i));
        }
        for (int i = 0; i < bin1.size(); i++){
            current.add("1" + bin1.get(i));
        }
        return current;
    }
    
    public static void main (String []args){
        new P9C();
    }
}
