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.*;

public class HexadecimalNumbers {

    private static final long[] numbers = new long[(1<<9) + 1];
    static {
        for ( int i = 0; i <= (1<<9); ++i ) {
            numbers[i] = convert(i);
            //System.out.println( numers[i] );
        }
    }

    private static long convert( int n ) {
        long res = 0;
        for ( int i = 10; i >= 0; --i) {
            res += (n & (1<<i)) > 0 ? 1 : 0; 
            res *= 10;
        }
        return res / 10;
    }

    public static void main( String[] args ) throws Exception {
        BufferedReader br = new BufferedReader( new InputStreamReader( System.in ) );
        int n = Integer.parseInt( br.readLine() );
        int idx = Arrays.binarySearch( numbers, n );
        System.out.println( idx < 0 ? -idx - 2 : idx );
    }

}
