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.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class Main {
	
	static long n = 0;

	public static void main(String[] args) throws Exception {
		try(BufferedReader br = new BufferedReader(new InputStreamReader(System.in))){
			n = Long.parseLong(br.readLine());
			System.out.println(get("0"));
		}
	}
	
	public static int get(String a) {
		boolean[] bools = {false, false, false};
		List<String> num = new ArrayList<>(Arrays.asList(a.split("")));
		int count = 0;
		
		num.remove("0");
		
		if(Long.parseLong(a) > n) return 0;
		
		for (String s : num) {
			int i = Integer.parseInt(s);
			if(i == 3) bools[0] = true;
			else if(i == 5) bools[1] = true;
			else if(i == 7) bools[2] = true;
			else {
				bools[0] = false;
				break;
			}
		}
		if(bools[0] && bools[1] && bools[2]) count++;
		if(Long.parseLong(a) == 0) a = "";
		
		for (String ss : "357".split("")) {
			count += get(a + ss);
		}
		return count;
		
	}

}