use std::io::stdin;

fn get_line() -> String {
    let mut line = String::new();
    stdin().read_line(&mut line).ok();
    line
}

fn main() {
    let n = get_line();
    let n: usize = n.trim().parse().unwrap();
    let line = get_line();
    let line: Vec<&str> = line.trim().split_whitespace().collect();
    let mut a: Vec<i32> = line.iter().map(|x| x.parse().unwrap()).collect();
    a.sort();

    if a.len() % 2 == 1 {
        println!("{}", a[n / 2] as f32)
    } else {
        println!("{}", (a[(n-1) / 2] as f32 + a[n / 2] as f32) / 2.0);
    }
}