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)

use std::io;
use std::io::prelude::*;

fn dfs(m: u64, n: u64) -> usize {
    if m > n {
        return 0;
    }
    let m_str = m.to_string();
    let flag = m_str.contains('3') && m_str.contains('5') && m_str.contains('7');
    return if flag { 1 } else { 0 }
        + dfs(m * 10 + 3, n)
        + dfs(m * 10 + 5, n)
        + dfs(m * 10 + 7, n);
}

fn main() {
    let mut stdin = io::stdin();
    let mut buf = String::new();
    let _ = stdin.read_to_string(&mut buf);
    let n: u64 = buf.trim().parse().unwrap();

    println!("{}", dfs(0, n));
}