use std::io::*;
use std::str::FromStr;

#[allow(dead_code)]
fn get_line() -> String {
    let stdin = stdin();
    let mut line = String::new();
    stdin.lock().read_line(&mut line).expect("io error.");
    line.trim().to_string()
}

#[allow(dead_code)]
fn cast<T: FromStr>(s: &str) -> T {
    s.parse().ok().expect("parse error.")
}

#[allow(dead_code)]
fn get_vec<T: FromStr>() -> Vec<T> {
    (&get_line()).split(' ').map(cast::<T>).collect()
}

fn main() {
    let pv: [u64; 6] = [2, 3, 5, 7, 11, 13];
    let cv: [u64; 6] = [4, 6, 8, 9, 10, 12];

    let k: u64 = cast(&get_line());
    let mut cnt: f64 = 0.;
    for p in pv.into_iter() {
        for c in cv.into_iter() {
            if p * c == k {cnt += 1.};
        }
    }

    println!("{:.15}", cnt / 36.);
}