use std::io;
use std::convert::TryFrom;

fn main() {
    let stdin = io::stdin();
    let mut n: String = String::new();
    stdin.read_line(&mut n).ok();
    let f:f32;
    loop
    {
        let n:i8 = match n.trim().parse() 
        {
            Ok(num) => num,
            Err(_) => continue,
        };
        if(n < 1 || n > 100) { continue; }
        f = 1.0/(n as f32);
        break;
    }
    print!("{:.6}",f);

}