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 Rust (1.15.1) (judge verdict: Accepted)

const NUMS_753: [u64; 3] = [7, 5, 3];

fn count(s: &String, c: char) -> u64 {
    let chars_vec: Vec<char> = s.chars().collect();
    chars_vec.iter().filter(|cmp_c| **cmp_c == c).count() as u64
}

fn dfs(num: u64, limit: u64) -> u64 {
    if num > limit {
        0
    }
    else {
        let is_753 = NUMS_753.iter().all(|n| {
            let c = std::char::from_digit(*n as u32, (*n + 6) as u32).unwrap();
            count(&num.to_string(), c) > 0
        });
        let sum: u64 = NUMS_753.iter().map(|n| {
            dfs(num * 10 + n, limit)
        }).sum();
        sum + if is_753 { 1 } else { 0 }
    }
}

fn main() {
    let limit: u64 = read();
    println!("{}", dfs(0, limit));
}

fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}