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 <bits/stdc++.h>
using namespace std;

long long dfs(string &S, long long n) {
    long long ret = 0;
    vector<char> list = {'3', '5', '7'};

    if ((int)S.size() > 0) {
        if (stoll(S) > n) {
            return ret;
        } else {
            bool flag = true;
            for (auto c : list) {
                if (S.find(c) == string::npos) {
                    flag = false;
                }
            }
            if (flag) {
                ret++;
            }
        }
    }
    
    for (auto c : list) {
        S.push_back(c);
        ret += dfs(S, n);
        S.pop_back();
    }
    return ret;
}


int main () {
    long long n;
    cin >> n;

    string S = "";
    long long ans = 0;

    ans = dfs(S, n);
    cout << ans << endl;

}