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)

fn rec(i: u64, n: u64) -> u64 {
    if i > n {
        return 0;
    }

    let s = i.to_string();
    let mut ret: u64 = 0;
    if ["3", "5", "7"].iter().all(|x| s.contains(x)) {
        ret += 1;
    }
    ret + [3, 5, 7]
        .iter()
        .map(|&x| rec(i * 10 + x, n))
        .fold(0, |sum, x| sum + x)
}

fn main() {
    let mut buf = String::new();
    std::io::stdin().read_line(&mut buf).ok();
    let n: u64 = buf.trim().parse().unwrap();
    println!("{}", rec(0, n));
}