fn main() {
  use std::io::prelude::*;
  let cin = std::io::stdin();
  let reader = std::io::BufReader::new(cin.lock());
  let mut lines = reader.lines();

  lines.next();
  let mut a: Vec<i64> = lines.next().unwrap().unwrap().split_whitespace().map(|x| x.parse().unwrap()).collect();
  a.sort();
  let m = a[a.len() / 2];
  let ans = a.into_iter().fold(0, |acc, x| acc + (x - m).abs());
  println!("{}", ans);
}