class Calc0198
  def initialize(args)
    args = args.map { |l| l.chomp.split(/\s+/) }
    @b = args.shift.first.to_i
    @n = args.shift.first.to_i
    @cs = args.map(&:first).map(&:to_i)
  end

  def run
    med = [@cs.sort[@n / 2], (@cs.inject(:+) + @b) / @n].min
    @cs.map { |c| (med - c).abs }.inject(:+)
  end
end

puts Calc0198.new(STDIN.readlines).run if __FILE__ == $0