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.*;

public class test 
{  
    static ArrayList<Integer> al=new ArrayList<Integer>();
    
    static void Get(int base, int n)
    {
	int x=(int)Math.pow(10,base);
	al.add(x);
	int end=al.size()-1;
	for(int i=0;i<end;i++)
	    if(x+al.get(i)>n)
		break;
	    else
		al.add(x+al.get(i));
    }
    public static void main(String[] args) 
    {
        Scanner in=new Scanner(System.in);
        int n=in.nextInt();

        int i=0;
        int m=n;
        
        while(m>0)
        {
            Get(i,n);
            i++;
            m/=10;
        }
        
        System.out.println(al.size());
    }
}


