class Chukei
  attr_reader :x, :y, :friends
  def initialize(x, y)
    @x = x.to_f
    @y = y.to_f
    @friends = []
  end

  def friend?(other)
    @friends.include?(other)
  end

  def denpa?(other)
    distance(other) <= 10
  end

  def add_friend(other)
    @friends << other
    @friends |= other.friends
  end

  def distance(other)
    return Math.sqrt((@x - other.x)**2 + (@y - other.y)**2)
  end

  def max_dist_friend
    m = -1
    @friends.each do |other|
      kyori = distance(other)
      m = kyori if kyori > m
    end
    return m
  end
end

n = gets.to_i
chukei_list = []
n.times do
  chukei_list << Chukei.new(*(gets.split.map(&:to_i)))
end

chukei_list.each do |chukei|
  chukei_list.each do |other|
    unless chukei.friend?(other)
      if chukei.denpa?(other)
        chukei.add_friend(other)
      end
    end
  end
end

m = -1
chukei_list.each do |chukei|
  chu_m = chukei.max_dist_friend
  m = chu_m if m < chu_m
end
if m == -1
  kotae = 2
else
  kotae = m + 2
end
puts kotae