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.Arrays;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        long n = in.nextLong();
        System.out.println(dfs("", n));
    }

    private static long dfs(String s, long n) {
        long res = 0;
        if (!s.isEmpty()) {
            if (check(s, n)) {
                res++;
            } else if (Long.parseLong(s) > n) {
                return 0;
            }
        }
        for (String next : Arrays.asList("7", "5", "3")) {
            res += dfs(s + next, n);
        }
        return res;
    }

    private static boolean check(String s, long n) {
        long sl = Long.parseLong(s);
        if (sl > n) {
            return false;
        }
        if (!s.contains("3") || !s.contains("5") || !s.contains("7")) {
            return false;
        }
        return true;
    }
}