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.*;
import java.io.*;

public class Main
{
    static class Reader {
		BufferedReader br;
		StringTokenizer st;
 
		public Reader() {
			br = new BufferedReader(new InputStreamReader(System.in));
		}
 
		String next() {
			while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}
 
		int nextInt() {
			return Integer.parseInt(next());
		}
 
		long nextLong() {
			return Long.parseLong(next());
		}
 
		double nextDouble() {
			return Double.parseDouble(next());
		}
 
		String nextLine() {
			String str = "";
			try {
				str = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return str;
		}
 
	}
	public static void main(String[] args) throws IOException 
	{
		Reader sc=new Reader();Main G=new Main();
		PrintWriter o = new PrintWriter(System.out);
		int n=sc.nextInt();
		String s=Integer.toString(n);
		int l=s.length();int c=0;
		//s=Integer.toBinaryString(n);
		for (int i=1;i<Math.pow(2,l);i++)
		{
		    
		    String s1=Integer.toBinaryString(i);
		    //o.println(s1.length()<s.length() );
		    if (s1.length()<s.length() || s.compareTo(s1)>=0)c++;
		    else break;
		}
		o.println(c);
		
        o.flush();
        o.close();
	}
} 