class Ichien
  attr_reader :point
  def initialize(x, y)
    @point = Complex(x, y)
  end
  def kasanaru(other)
    (@point - other.point).abs < 20
  end
end

n = gets.to_i
list = []
n.times do
  ichi = Ichien.new(*gets.split.map(&:to_f))
  okeru = true
  list.each do |oita|
    if ichi.kasanaru(oita)
      okeru = false
      break
    end
  end
  if okeru
    list << ichi
  end
end

puts list.size