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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.*;
class Main{
    static long n;
    static List<Long> list;
    public static void main(String[] args){
        Scanner scanner = new Scanner(System.in);
        list = new ArrayList<>();
        n = scanner.nextLong();
        dfs("3");
        dfs("5");
        dfs("7");
        int count = 0;
        for(int i = 0; i < list.size(); i++){
            String cur = String.valueOf(list.get(i));
            if(cur.contains("3") && cur.contains("5") && cur.contains("7")){
                count++;
            }
        }
        System.out.println(count);
    }
    public static void dfs(String s){
        if(Long.parseLong(s) <= n){
            list.add(Long.parseLong(s));
            String[] target = {"3", "5", "7"};
            for(int i = 0; i < target.length; i++){
                String newS = s + target[i];
                dfs(newS);
            }
        }
    }
}