n=gets.to_i
MAX=20000
DIV=14
l=(0..MAX/DIV+2).map{[]}
n.times{
  x,y=gets.split.map(&:to_i)
  vx,vy=x/DIV,y/DIV
  d=[*vx-2..vx+2].product([*vy-2..vy+2])
  if d.select{|ux,uy|l[ux][uy]}.all?{|ux,uy|tx,ty=l[ux][uy];(tx-x)**2+(ty-y)**2>=400}
    l[vx][vy]=[x,y]
  end
}
p l.inject(0){|s,i|s+i.compact.size}