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.Scanner;


public class NPrimeFactors {

    public static void main(String[] args){
        Scanner input = new Scanner(System.in);
        while(input.hasNext()){
            System.out.println(getBin(input.nextLong()));
        }
        input.close();
    }
    
    public static long getBin(long num){
        char[] chars = (num+"").toCharArray();
        String newNum = "";
        for(int a=0; a<chars.length; a++)
            if(chars[a] > '1'){
                for(; a<chars.length; a++)
                    newNum += "1";
                break;
            }else newNum += chars[a];
                
        return Long.parseLong(newNum, 2);
    }
    
}
