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.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.lang.reflect.Array;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.text.DecimalFormat;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Map.Entry;
import java.util.Queue;
import java.util.Scanner;
import java.util.Set;
import java.util.Stack;
import java.util.StringTokenizer;
import java.util.TreeMap;

 
 
public class Main {
	static ArrayList<Integer> a = new ArrayList<Integer>();
	public static void main(String[] args) throws IOException{
		  	FastScanner sc = new FastScanner();
			PrintWriter out = new PrintWriter(System.out);
			int n =sc.nextInt();
			generate(1);
			Collections.sort(a);
			for(int i=0;i<a.size();i++){
				if(a.get(i)>n){
					System.out.println(i);
					return;
				}
			}
			
			
			
			
	}
	static void generate(int x){
		if(x<=1e10)
			a.add(x);
		if(x>1e9)return ;
		
		generate(x*10);
		generate(x*10+1);
		
	}


	

	
	
		
	
			
		
	

			

			
			
			
	
	



	
	
			    
			


			
			
	
	
	

			
	
		
	
	
	
		

			

		

	
	

	
	
	

			
						
			

	
	

		
		
		


















































	static void shuffle(int[] a)
	{
		int n = a.length;
		for(int i = 0; i < n; ++i)
		{
			int r = i + (int)(Math.random() * (n - i));
			int tmp = a[r];
			a[r] = a[i];
			a[i] = tmp;
		}
	}


	static void generate(int[] p, int L, int R) {
		  if (L == R) {
		      
		      
		  }else { 
		    for (int i = L; i <= R; i++) {
		    	int tmp = p[L]; p[L] = p[i]; p[i] = tmp;//swap  do
		      generate(p, L+1, R);//recurse 
		      tmp = p[L]; p[L] = p[i]; p[i] = tmp;//unswap  undo

		    }
		  }
		}


















































































































	
}
	 


	 class point implements Comparable{
		int x ;int y ;
		point(int x ,int y){
			this.x=x;
			this.y=y;
		}
		@Override
		public int compareTo(Object arg0) {
			// TODO Auto-generated method stub
			point p = (point)arg0;
			if(p.x>this.x)return -1;
			if(p.x<this.x)return 1;
			if(p.x==this.x){
				if(p.y>this.y)return -1;
				if(p.y<this.y)return 1;
			}
			return 0;
		}
		
	}
	
	
	











	
 
 
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
class FastScanner {
 
 
 
 
    BufferedReader br;
    StringTokenizer st;
 
    public FastScanner() {
        br = new BufferedReader(new InputStreamReader(System.in));
    }
 
    public FastScanner(String s) {
        try {
            br = new BufferedReader(new FileReader(s));
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }
 
    String nextToken() {
        while (st == null || !st.hasMoreElements()) {
            try {
 
                st = new StringTokenizer(br.readLine());
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return st.nextToken();
    }
 
    int nextInt() {
        return Integer.parseInt(nextToken());
    }
 
    long nextLong() {
        return Long.parseLong(nextToken());
    }
 
    double nextDouble() {
        return Double.parseDouble(nextToken());
    }
 
 
}