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.Scanner;

public class HexadecimalNumbers {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int l = 0;
        int n2=n;
        while(n2>0){
            n2/=10; l++;
        }
        int res = getPossible(l-1,0,n);
        System.out.println(res);
    }
    
    public static int getPossible(int pos, int sum, int n){
        if(pos==-1){
            return sum>0?1:0;
        }
        int p10 = (int) Math.pow(10,pos);
        int res =0;
        if( sum + p10 <= n){
            res += getPossible(pos-1, sum+p10, n);
        }
        res+=getPossible(pos-1, sum, n);
        return res;
    }
    
    
}
