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.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		String str = String.valueOf(n);
		int len = str.length();
		
		List<String> list = new ArrayList<String>();
		dfs(list,"",len);
		int count = 0;
		for(int i=0; i<list.size(); i++) {
			if(Integer.parseInt(list.get(i))<=n) {
				count++;
			}
		}
		System.out.println(count);
	}

	private static void dfs(List<String> list, String res, int len) {
		if(res.length() == len+1) {
			return;
		}else {
			if(res.contains("7")&&res.contains("5")&&res.contains("3")) {
				list.add(res);
			}
			dfs(list, res + "7", len);
			dfs(list, res + "5", len);
			dfs(list, res + "3", len);
		}
	}
}