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.util.Arrays;
import java.util.Scanner;


public class Prob009C
{
    public static void main( String[] Args )
    {
        int[] worked = new int[1000];
        Arrays.fill( worked, Integer.MAX_VALUE );

        worked[0] = 1;
        int index = 0;
        int lastIndex = 1;
        while ( worked[lastIndex - 1] <= 1000000000 )
        {
            worked[lastIndex++] = worked[index] * 10;
            worked[lastIndex++] = worked[index++] * 10 + 1;
        }

        Scanner scan = new Scanner( System.in );
        int x = scan.nextInt();

        int answer = Arrays.binarySearch( worked, x );
        System.out.println( Math.max( answer + 1, -answer - 1 ) );
    }
}
