Codeforce 9C

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.

Example

Input

10

Output

2

Note

For n = 10 the answer includes numbers 1 and 10.

 

给你一个数，求1到这个数中有多少个只有1，0组成的数

解题思路：可以深搜，也可以直接构造

#include<stdio.h>

long long sum, sum1;

void dfs(long long a) {
    if(sum<a)
        return ;
    sum1++;
    dfs(a*10);
    dfs(a*10+1);
}

int main() {
    while(scanf("%lld", &sum)!=EOF) {
        sum1 = 0;
        
        dfs(1);
    
        printf("%lld
", sum1);
    }
    return 0;
}