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 (GCC 5.4.1) (judge verdict: Accepted)

#include <iostream>
#include <string>
#include <algorithm>
using namespace std;

template <class T>
bool contain(const std::string &s, const T &v)
{
    return s.find(v) != std::string::npos;
}

int cnt = 0;

int dfs(int n, string s, long t){
    if(s.size() == n){
        if (contain(s, "3") && contain(s, "5") && contain(s, "7") && stoi(s) <= t)
        {
            cnt++;        
        }
        return cnt;
    }

    dfs(n, s+"3", t);
    dfs(n, s+"5", t);
    dfs(n, s+"7", t);
    return cnt;
}

int main(){
    string n;
    cin>>n;
    for(int i=3; i<=n.size(); i++){
        dfs(i, "", stoi(n));
    }
    cout << cnt << endl;
}