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)

#![allow(unused_imports)]

use proconio::{input, fastout};
use proconio::marker::*;

#[fastout]
fn main() {
    input! {
    n: usize
    }
    let ans = dfs(&vec![], n);
    println!("{}", ans);
}

fn dfs(d: &Vec<usize>, n: usize) -> usize {
    if n < vec_to_num(d) {
        return 0;
    }
    let mut res = 0;
    if (3..=7).step_by(2).all(|x| d.contains(&x)){
        res += 1;
    }
    for i in 0..3 {
        let mut nd = d.clone();
        nd.push(i * 2 + 3);
        res += dfs(&nd, n)
    }
    res
}

fn vec_to_num(d: &Vec<usize>) -> usize {
    let mut res = 0;
    for &i in d {
        res = res * 10 + i;
    }
    res
}