macro_rules! input {
  (source = $s:expr, $($r:tt)*) => {
    let mut iter = $s.split_whitespace();
    let mut next = || { iter.next().unwrap() };
    input_inner!{next, $($r)*}
  };
  ($($r:tt)*) => {
    let stdin = std::io::stdin();
    let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock()));
    let mut next = move || -> String{
      bytes
        .by_ref()
        .map(|r|r.unwrap() as char)
        .skip_while(|c|c.is_whitespace())
        .take_while(|c|!c.is_whitespace())
        .collect()
    };
    input_inner!{next, $($r)*}
  };
}

macro_rules! input_inner {
  ($next:expr) => {};
  ($next:expr, ) => {};

  ($next:expr, $var:ident : $t:tt $($r:tt)*) => {
    let mut $var = read_value!($next, $t);
    input_inner!{$next $($r)*}
  };
}

macro_rules! read_value {
  ($next:expr, ( $($t:tt),* )) => {
    ( $(read_value!($next, $t)),* )
  };

  ($next:expr, [ $t:tt ; $len:expr ]) => {
    (0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
  };

  ($next:expr, chars) => {
    read_value!($next, String).chars().collect::<Vec<char>>()
  };

  ($next:expr, usize1) => {
    read_value!($next, usize) - 1
  };

  ($next:expr, $t:ty) => {
    $next().parse::<$t>().expect("Parse error")
  };
}

fn main() {
    input! {
      n: usize,
      a: [i32; n],
    }

    a.sort_unstable();

    match n % 2 {
        0 => println!("{:.1}", ((a[n / 2 - 1] + a[n / 21]) * 10 / 2) as f32 / 10.0),
        _ => println!("{}", a[n / 2]),
    }
}