class Calc0021
  def initialize(args)
    args = args.map { |l| l.chomp.split(/\s+/) }
    @n = args.shift.first.to_i
    @k = args.shift.first.to_i
    @ns = args.map(&:first).map(&:to_i)
  end

  def run
    ns = @ns.sort
    ns.last - ns.first
  end
end

puts Calc0021.new(STDIN.readlines).run if __FILE__ == $0