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.util.*;
import java.math.*;
/**
 * 
 * @author Erasyl Abenov (abenov.erasyl@gmail.com);
 * 
 */
public class Main {
    public static void main(String[] args) throws IOException {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
            try (PrintWriter out = new PrintWriter(outputStream)) {
                TaskB solver = new TaskB();
                solver.solve(1, in, out);
            }
    }
}
class TaskB {
    private static int gcd(int a, int b){
        if(b == 0) return a;
        return gcd(b, a%b);
    }
    public void solve(int testNumber, InputReader in, PrintWriter out) throws IOException{
        int n = in.nextInt();
        int i = 0;
        while(true){
            i++;
            long num = Long.parseLong(Integer.toString(i, 2));
            if(num > n){
                out.println(i - 1);
                return;
            }
        }
    }
} 


class InputReader {
    private final BufferedReader reader;
    private StringTokenizer tokenizer;
    public InputReader(InputStream stream) {
        reader = new BufferedReader(new InputStreamReader(stream));
        tokenizer = null;
    }
       
    public String nextLine() {
        try {
            return reader.readLine();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
       
    public String next() {
        while (tokenizer == null || !tokenizer.hasMoreTokens()) {
            tokenizer = new StringTokenizer(nextLine());
        }
        return tokenizer.nextToken();
    }
       
    public int nextInt() {
        return Integer.parseInt(next());
    }
    public BigInteger nextBigInteger(){
        return new BigInteger(next());
    }
    public BigDecimal nextBigDecimal(){
        return new BigDecimal(next());
    }
    public long nextLong() {
        return Long.parseLong(next());
    }
    public double nextDouble() {
        return Double.parseDouble(next());
    }
}