use std::io::stdin;
pub fn main() {
    let line = || {
        let mut buf = String::new();
        let _ = stdin().read_line(&mut buf);
        buf
    };
    let n: usize = line().trim().parse().unwrap();
    let mut v: Vec<i32> = line().split_whitespace().flat_map(|x| x.parse()).collect();
    v.sort();
    let answer: f64 = match n % 2 {
        0 => (v[n / 2 - 1] + v[n / 2]) as f64 / 2.0,
        _ => v[n / 2] as f64,
    };
    println!("{:.1}", answer);
}