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::marker::Chars;
use proconio::{fastout, input};
// use std::cmp::{max, min};

#[fastout]
fn main() {
    input! {
        n: usize
    };

    let n: usize = n;
    let mut v = vec![0; n.to_string().len()];

    let count = dfs(n, &mut v, 0);

    println!("{}", count);
}

fn dfs(base: usize, v: &mut Vec<usize>, i: usize) -> usize {
    let mut count = 0;

    if base.to_string().len() == i {
        let mut sum = 0;
        for (i, vi) in v.iter().rev().enumerate() {
            sum += vi * 10i32.pow(i as u32) as usize;
        }

        if sum <= base && v.contains(&5) && v.contains(&3) && v.contains(&7) {
            count += 1;
        }
    } else {
        let x = vec![0, 3, 5, 7];

        for &xi in x.iter() {
            if xi == 0 && (v.contains(&5) || v.contains(&3) || v.contains(&7)) {
                continue;
            }

            v[i] = xi;
            count += dfs(base, v, i + 1)
        }
    }
    count
}