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.*;

public class Main {
    static int n, cnt;
    static StreamTokenizer st = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
    static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

    static void dfs(int u) {
        if (u > n) {
            return;
        }
        ++cnt;
        dfs(u * 10);
        dfs(u * 10 + 1);
    }

    public static void main(String[] args) throws IOException {
        // st = new StreamTokenizer(
        // new BufferedReader(new InputStreamReader(new FileInputStream("/Users/huangweixuan/testdata.txt"))));
        st.nextToken();
        n = (int)st.nval;
        dfs(1);
        bw.write(cnt + "");
        bw.close();
    }
}