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 (1.42.0) (judge verdict: Accepted)

use std::io;
use std::str::FromStr;
use std::collections::HashSet;

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

fn digit(n: u64) -> u64 {
    if n == 0 {
        return 1;
    }
    for i in 0..20u32 {
        if n < 10u64.pow(i) {
            return i as u64;
        }
    }
    20u64
}

fn main() {
    let n: u64 = input();
    let digit = digit(n);
    let k = 3u64;
    let mut count = 0;
    for d in 3..(digit+1) {
        for mask in 0..k.pow(d as u32) {
            let mut tmp = mask;
            let mut num: u64 = 0;
            for i in 0..d {
                let val = tmp % k;
                match val {
                    0 => num = num * 10 + 7,
                    1 => num = num * 10 + 5,
                    2 => num = num * 10 + 3,
                    _ => print!("0")
                }
                tmp /= k;
            }
            if num <= n {
                let c: Vec<char> = num.to_string().chars().collect();
                if c.contains(&'7') && c.contains(&'5') && c.contains(&'3') {
                    // println!("{}", num);
                    count += 1;
                }
            }
        }
    }
    println!("{}", count);
}