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 (1.15.1) (judge verdict: Accepted)

fn cand_755(N: u64, value: u64) -> Vec<u64> {
    let mut result = Vec::new();
    if value + 3 <= N {
        result.push(value + 3);
        result.append(&mut cand_755(N, (value + 3) * 10));
    }
    if value + 5 <= N {
        result.push(value + 5);
        result.append(&mut cand_755(N, (value + 5) * 10));
    }
    if value + 7 <= N {
        result.push(value + 7);
        result.append(&mut cand_755(N, (value + 7) * 10));
    }
    return result;
}

fn c_755() {
    let mut input = String::new();
    std::io::stdin().read_line(&mut input).expect("input error");
    let N = input.trim_right().parse::<u64>().expect("parse error");

    let mut candidate = cand_755(N, 0);

    let count = candidate.iter()
        .filter_map(|n| {
            let snv: Vec<char> = n.to_string()
                .chars()
                .collect();
            if snv.iter().any(|&x| x == '3') &&
                snv.iter().any(|&x| x == '5') &&
                snv.iter().any(|&x| x == '7') {
                return Some(n);
            }
            else {
                return None;
            }
        }).count();
    println!("{}", count);
}

fn main() {
    c_755();
}