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: u64,
    }

    let mut ret = 0;
    let tmp = [3, 5, 7];
    let mut v: Vec<u64> = Vec::new();
    for i in tmp.iter() {
        v.push(*i);
        ret += dfs(&mut v, n);
        v.pop();
    }
    println!("{}", ret);
}

fn make_num(v: &Vec<u64>) -> u64 {
    let n = v.len();
    let mut ret = 0;
    for i in 0..n {
        ret = ret * 10 + v[n - 1 - i];
    }
    ret
}

fn dfs(v: &mut Vec<u64>, n: u64) -> u64 {
    if make_num(v) > n {
        return 0;
    }

    let tmp = [3, 5, 7];
    let mut ret = 0;
    for i in tmp.iter() {
        v.push(*i);
        ret += dfs(v, n);
        v.pop();
    }

    if v.iter().any(|&x| x == 3) && v.iter().any(|&x| x == 5) && v.iter().any(|&x| x == 7) {
        ret + 1
    } else {
        ret
    }
}