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 proconio::input;

fn main() {
    input! {
        n: usize,
    }

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

fn is_753(n: usize) -> bool {
    let mut n = n;
    let mut has_7 = false;
    let mut has_5 = false;
    let mut has_3 = false;

    while n > 0 {
        let d = n % 10;
        n /= 10;

        match d {
            7 => { has_7 = true; },
            5 => { has_5 = true; },
            3 => { has_3 = true; },
            _ => {},
        }
        if has_7 && has_5 && has_3 {
            break;
        }
    }

    has_7 && has_5 && has_3
}

fn dfs(max:usize, num: usize) -> usize {
    if num > max {
        return 0;
    }
    let mut ret = if is_753(num) { 1 } else { 0 };
    let num = num * 10;
    ret += dfs(max, num + 3);
    ret += dfs(max, num + 5);
    ret += dfs(max, num + 7);
    ret
}