N = gets.to_i
xy = []

N.times do |i|
  xy << gets.split.map(&:to_i)
end

xyc = Hash.new(0)

xy.sort_by! {|a| a[0] }

0.upto(N-2) do |i|
  x = xy[i+1][0] - xy[i][0]
  y = xy[i+1][1] - xy[i][1]
  xyc[ [x, y] ] += 1
end

puts xyc.size