n = gets.chop.to_i
x = []
y = []
n.times do
  line = gets.chop.split.map(&:to_i)
  x << line.shift
  y << line
end

x=x.flatten
y=y.flatten

h=[]

for i in 0...n
  h[i]=[x[i],y[i]]
end

res = []

for i in 0...n
  for j in 0...n
    xx=h[j][0]-h[i][0]
    yy=h[j][1]-h[i][1]
    if(!((xx==0 && yy==0) || (xx<0) || (yy<0) ))
    	res[i*n+j]=[xx,yy]
    end
  end
end

res.compact!

res_res=(res.flatten.length-res.uniq.flatten.length)/2
if(res_res==0)
  puts 1
else
  puts res_res
end
