fn main(){
    let mut sc = Scanner::new();
    while let Ok(n) = sc.wrapped::<usize>() {
        let mut a: Vec<i32> = vec![0; n];
        for i in 0..n { a[i] = sc.next(); }
        a.sort();
        println!("{}", if n%2 == 1 {
            a[n/2] as f64
        } else {
            (a[n/2-1] + a[n/2]) as f64 / 2.0
        });
    }
}

#[allow(dead_code)]
struct Scanner {
    token_buffer : Vec<String>,
    index : usize,
}

#[allow(dead_code)]
impl Scanner {
    fn new() -> Scanner {
        Scanner { token_buffer: vec![], index: 0 }
    }

    fn wrapped<T>(&mut self) -> Result<T,&str> where T: std::str::FromStr {
        let s = try!(self.fetch_token());
        let t = try!(s.parse::<T>().map_err(|_| "Parse error"));
        Ok(t)
    }
    fn next<T>(&mut self) -> T where T: std::str::FromStr {
        self.wrapped::<T>().unwrap()
    }

    fn fetch_token(&mut self) -> Result<&String,&str> {
        while self.index >= self.token_buffer.len() {
            let mut st = String::new();
            while st.trim() == "" {
                match std::io::stdin().read_line(&mut st) {
                    Ok(l) if l > 0 => continue,
                    Ok(_)  => return Err("End of file"),
                    Err(_) => return Err("Failed to read line"),
                }
            }
            self.token_buffer = st.split_whitespace()
                .map(|x| x.to_string())
                .collect();
            self.index = 0;
        }

        self.index += 1;
        Ok(&self.token_buffer[self.index - 1])
    }
}