N = gets.to_i
A = $<.map{|s|s.split.map &:to_i}
A.map!{|a|a.sort}.sort!

$dp = {}
def f(i)
  $dp[i] ||= if i < 0
    0
  else
    (0...i).map{|j|
      1 + f(j) if A[j].zip(A[i]).all?{|a,b|a < b}
    }.compact.max || 1
  end
end

p f(N-1)