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.IOException;
import java.io.InputStreamReader;

public class HexadecimalNumbers {

	public static void main(String[] args) throws NumberFormatException, IOException {

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(br.readLine());
		String s = n+"";
		int length = s.length(), sum = 0;
		StringBuilder sb = new StringBuilder("");
		
		for(int i = 0; i < length; i++)
			if(s.charAt(i) > '1')
				for(;i < length; i++)
					sb.append('1');
			else if(s.charAt(i) == '1')
				sb.append(1);
			else
				sb.append('0');
		
		for(int i = 0; i < length ; i++)
			if(sb.charAt(i) == '1')
				sum += 1 <<(length-i-1);
		System.out.println(sum);
	}
}
