fn main() {
    let stdin = std::io::read_to_string(std::io::stdin()).unwrap();
    let mut stdin = stdin.split_ascii_whitespace();

    let k: u8 = stdin.next().unwrap().parse().unwrap();

    use std::io::Write;
    std::io::stdout()
        .write_all(output(solve(k)).as_bytes())
        .unwrap();
}

fn solve(k: u8) -> f64 {
    const PRIMES: [u8; 6] = [2, 3, 5, 7, 11, 13];
    const NOT_PRIMES: [u8; 6] = [4, 6, 8, 9, 10, 12];
    let mut count = 0;

    PRIMES.into_iter().for_each(|p| {
        NOT_PRIMES.iter().for_each(|&n| {
            if n * p == k {
                count += 1
            }
        })
    });

    count as f64 / 36.0
}

fn output(ans: f64) -> String {
    format!("{:>.013}", ans) + "\n"
}