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.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.InputMismatchException;

public class CFbR9C{

	void solve()
	{
		int n = ni();
		char[] s = Integer.toString(n).toCharArray();
		boolean m = false;
		for(int i=0;i<s.length;i++)
		{
			if(m)
			{
				s[i] = '1';
				continue;
			}
			if(s[i]>='2')
			{
				m = true;
				s[i] = '1';
				continue;
			}
		}
		out.println(Integer.parseInt(new String(s),2));
	}
	
	public static void main(String[] args){new CFbR9C().start();}
	
	private byte[] bufferArray = new byte[1024];
	private int bufLength = 0;
	private int bufCurrent = 0;
	InputStream inputStream;
	PrintWriter out;
	
	void start()
	{
		inputStream = System.in;
		out = new PrintWriter(System.out);
		solve();
		out.flush();
	}
	
	int nextByte()
	{
		if(bufLength==-1)
			throw new InputMismatchException();
		if(bufCurrent>=bufLength)
		{
			bufCurrent = 0;
			try
			{bufLength = inputStream.read(bufferArray);}
			catch(IOException e)
			{ throw new InputMismatchException();}
			if(bufLength<=0)
				return -1;
		}
		return bufferArray[bufCurrent++];
	}
	
	boolean isSpaceChar(int x)
	{return (x<33 || x>126);}
	
	boolean isDigit(int x)
	{return (x>='0' && x<='9');}
	
	int nextNonSpace()
	{
		int x;
		while((x=nextByte())!=-1 && isSpaceChar(x));
		return x;
	}
	
	int ni()
	{
		long ans = 0;
		boolean m = false;
		int x = nextNonSpace();
		if(x=='-') 
		{
			m = true;
			x = nextByte();
		}
		while(!isSpaceChar(x))
		{
			if(isDigit(x))
			{
				ans = ans*10 + x -'0';
				x = nextByte();
			}
			else
				throw new InputMismatchException();
		}
		if(ans<=Integer.MAX_VALUE && ans>=Integer.MIN_VALUE)
		{
			int k = (int)ans;
			return m ? -k:k;
		}
		else
			throw new InputMismatchException();
	}
	
	long nl()
	{
		long ans = 0;
		boolean m = false;
		int x = nextNonSpace();
		if(x=='-') 
		{
			m = true;
			x = nextByte();
		}
		while(!isSpaceChar(x))
		{
			if(isDigit(x))
			{
				ans = ans*10 + x -'0';
				x = nextByte();
			}
			else
				throw new InputMismatchException();
		}
		return m ? -ans:ans;
	}
	
	String ns()
	{
		StringBuilder sb = new StringBuilder();
		int x = nextNonSpace();
		while(!isSpaceChar(x))
		{
			sb.append((char)x);
			x = nextByte();
		}
		return sb.toString();
	}
	
	String nL()
	{
		StringBuilder sb = new StringBuilder();
		int x = nextNonSpace();
		while(x==32 || !isSpaceChar(x))
		{
			sb.append((char)x);
			x = nextByte();
		}
		return sb.toString();
	}
	
	char nc()
	{ return (char)nextNonSpace();}
	
	double nd()
	{ return (double)Double.parseDouble(ns()); }
	
	char[] ca()
	{ return ns().toCharArray();}
	
	char[] ca(int n)
	{
		char[] ans = new char[n];
		int p =0;
		int x = nextNonSpace();
		while(p<n)
		{
			ans[p++] = (char)x;
			x = nextByte();
		}
		return ans;
	}
	
	int[] ia(int n)
	{
		int[] ans = new int[n];
		for(int i=0;i<n;i++)
			ans[i]=ni();
		return ans;
	}
	
	long[] la(int n)
	{
		long[] ans = new long[n];
		for(int i=0;i<n;i++)
			ans[i] = nl();
		return ans;
	}
	
}
