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.HashMap;
import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;


public class two {
	public static void main(String args[])
	{
		Scanner get=new Scanner(System.in);
		String temp=get.nextLine();
		int count=0;
		for(int i=1;;i++)
		{
			StringBuffer t=new StringBuffer("");
			int tt=i,tt1=i;
			for(int j=0;tt1!=0;j++)
			{
				if((tt&1<<j)!=0)
					t.insert(0,"1");
				else
					t.insert(0,"0");
				tt1/=2;
			}
			//System.out.println(t);
			if(Integer.parseInt(String.valueOf(t))<=Integer.parseInt(temp))
				count++;
			else 
				break;
			//if(count==5)
			//	break;
			
		}
		System.out.println(count);
	}
}
