Problem:
Score : 300 points

Problem Statement

You are given an integer N. Among the integers between 1 and N (inclusive), how many Shichi-Go-San numbers (literally "Seven-Five-Three numbers") are there?

Here, a Shichi-Go-San number is a positive integer that satisfies the following condition:

When the number is written in base ten, each of the digits 7, 5 and 3 appears at least once, and the other digits never appear.

Constraints

1 \leq N < 10^9

N is an integer.

Input

Input is given from Standard Input in the following format:

N

Output

Print the number of the Shichi-Go-San numbers between 1 and N (inclusive).

Sample Input 1

575

Sample Output 1

4

There are four Shichi-Go-San numbers not greater than 575: 357, 375, 537 and 573.

Sample Input 2

3600

Sample Output 2

13

There are 13 Shichi-Go-San numbers not greater than 3600: the above four numbers, 735, 753, 3357, 3375, 3537, 3557, 3573, 3575 and 3577.

Sample Input 3

999999999

Sample Output 3

26484

Solution in C++14 (Clang 3.8.0) (judge verdict: Accepted)

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <vector>

using namespace std;

const long long bound=1000000000LL;
vector <long long> arr;
void dfs(long long cur,bool f3,bool f5,bool f7)
{
    if(f3&&f5&&f7)
        arr.push_back(cur);
    if(cur>bound)
        return ;
    dfs(cur*10+3,true,f5,f7);
    dfs(cur*10+5,f3,true,f7);
    dfs(cur*10+7,f3,f5,true);
    return ;
}

void init()
{
    arr.clear();
    dfs(0,false,false,false);
    sort(arr.begin(),arr.end());
}

int main()
{
    init();
    long long x;
    while(scanf("%lld",&x)!=EOF)
    {
        int tmp=upper_bound(arr.begin(),arr.end(),x)-arr.begin();
        printf("%d\n",tmp);
    }
    return 0;
}