#!/usr/bin/env perl

use strict;
use warnings;

my $n = <>;
my @ys = split / /, <>;
@ys = sort { $a <=> $b } @ys;
my $target;
if ($n % 2) {
  $target = $ys[$n / 2];
} else {
  my $lpos = int($n / 2);
  $target = ($ys[$lpos] + $ys[$lpos + 1]) / 2;
}
my $ans = 0;
for my $e (@ys) {
  $ans += abs($e - $target);
}
print "$ans\n";