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.*;
import static java.lang.Math.*;
import static java.util.Arrays.*;

public class Main {
    static void dbg(Object... o){
        System.out.println(deepToString(o));
    }
    
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        
        int[] pow10 = new int[10];
        pow10[0]=1;
        for(int i=1; i<=9; i++) pow10[i]=10*pow10[i-1];
        
        int n = sc.nextInt();
        int ans = 0;
        for(int i = 1; i <= 512; i++){
            int k = 0;
            for(int j = 0; j <= 9; j++) if((i & (1<<j)) > 0) k += pow10[j];
            if(k <= n){
                ans++;
            }
        }
        System.out.println(ans);
    }
}
