fn run() {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).unwrap();
    let n: i32 = s.trim().parse().unwrap();
    let mut ans = 0f64;
    for i in (1..=10000).rev() {
        ans += (1.0 / i as f64).powi(n);
    }
    println!("{:.7}", ans);
}

fn main() {
    run();
}