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::{fastout, input};

#[fastout]
fn main() {
    input!(n: usize);
    let mut count: usize = 0;
    dfs(n, 0, &mut count, 0, 0, 0);
    println!("{}", count);
}

fn dfs(n: usize, a: usize, count: &mut usize, x: usize, y: usize, z: usize) {
    if a <= n && x >= 1 && y >= 1 && z >= 1 {
        *count += 1
    }
    if a >= n {
        return;
    }
    dfs(n, a * 10 + 3, count, x + 1, y, z);
    dfs(n, a * 10 + 5, count, x, y + 1, z);
    dfs(n, a * 10 + 7, count, x, y, z + 1);
}