#[macro_use]
mod input {

use std;
use std::io;

const SPLIT_DELIMITER: char = ' ';

#[macro_export]
#[allow(unused_macros)]
macro_rules! input {
    ( $($x:expr ),*) => {
        {
            let temp_str = input_line_str();
            let mut split_result_iter = temp_str.split_whitespace();
                $(
                let buf_split_result = split_result_iter.next();
                let buf_split_result = buf_split_result.unwrap();
                    ($x) = buf_split_result.parse().unwrap();
                )*
        }
    };
}

#[allow(dead_code)]
pub fn input_line_str() -> String {
    let mut s = String::new();
    io::stdin().read_line(&mut s).unwrap();
    s.trim().to_string()
}

#[allow(dead_code)]
pub fn p<T>(t: T)
where
    T: std::fmt::Display,
{
    println!("{}", t);
}

#[allow(dead_code)]
pub fn input_vector2d<T>(line: usize) -> Vec<Vec<T>>
where
    T: std::str::FromStr,
{
    let mut v: Vec<Vec<T>> = Vec::new();

    for _ in 0..line {
        let vec_line = input_vector();
        v.push(vec_line);
    }
    v
}

#[allow(dead_code)]
pub fn input_vector<T>() -> Vec<T>
where
    T: std::str::FromStr,
{
    let mut v: Vec<T> = Vec::new();

    let s = input_line_str();
    let split_result = s.split(SPLIT_DELIMITER);
    for z in split_result {
        let buf = match z.parse() {
            Ok(r) => r,
            Err(_) => panic!("Parse Error"),
        };
        v.push(buf);
    }
    v
}

#[allow(dead_code)]
pub fn str2vec(s: &str) -> Vec<char> {
    let mut v: Vec<char> = Vec::new();
    for c in s.chars() {
        v.push(c);
    }
    v
}
}

use input::*;

fn next_753(v: &mut Vec<usize>, n: usize) {
    if v[n] == 0 {
        v[n] = 3;
    } else if v[n] == 3 {
        v[n] = 5;
    } else if v[n] == 5 {
        v[n] = 7;
    } else {
        v[n] = 3;
        next_753(v, n - 1);
    }
}

fn is_753(v: &Vec<usize>) -> bool {
    let (mut f3, mut f5, mut f7): (bool, bool, bool) = (false, false, false);
    for z in v {
        if *z == 3 {
            f3 = true;
        }
        if *z == 5 {
            f5 = true;
        }
        if *z == 7 {
            f7 = true;
        }
        if f3 && f5 && f7 {
            return true;
        }
    }
    false
}

fn convert(v: &Vec<usize>) -> usize {
    let mut ans = 0;
    for z in v {
        ans *= 10;
        ans += *z;
    }
    ans
}

fn main() {
    let n: usize;
    let mut ans = 0;
    input!(n);

    let mut v = vec![0; n.to_string().len() + 1];

    while convert(&v) <= n {
        next_753(&mut v, n.to_string().len());
        if is_753(&v) {
            ans += 1;
        }
    }
    p(ans);
}