Hexadecimal's Numbers

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在一个程序世界中，病毒Megabyte尝试通过加载数字到其妹妹Hexadecimal的记忆中获取能量控制权，但由于Hexadecimal仅能识别二进制数，导致部分数字无法被加载。本题需找出在1到n范围内能成功加载的数字数量。

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

Output

Note

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

题解：水题一道；

代码：

#include <stdio.h>
#include <stdlib.h>
int n,m;
int sum;
int qiujie(int m)
{
    if(m>n) return 0;
    else sum++;
    qiujie(m*10);
    qiujie(m*10+1);
}
int main()
{
    scanf("%d",&n);
    sum=0;
    qiujie(1);
    printf("%d\n",sum);
    return 0;
}