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.*;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.Scanner;

public class cf2d9c {
	//PrintWriter out;
    public static void main(String[] args) throws IOException {
		//System.setIn(new FileInputStream("input.txt"));
		//System.setOut(new PrintStream("output.txt"));
        BufferedReader r = new BufferedReader(new InputStreamReader(System.in));
	int n = Integer.parseInt(r.readLine());
	int a = 1, ans = 0;
	while(a < 1024){
		String s = Integer.toBinaryString(a);
		int b = Integer.parseInt(s);
		if(b <= n) ans++;
		a++;
	}
	System.out.println(ans);
	}
}
