class Calc0182
  def initialize(args)
    args = args.map { |l| l.chomp.split(/\s+/) }
    @n = args.shift.first.to_i
    @as = args.shift.map(&:to_i)
  end

  def run
    @as.group_by(&:itself).select { |k, as| as.size == 1 }.size
  end
end

puts Calc0182.new(STDIN.readlines).run if __FILE__ == $0