n = (gets || "").chomp.to_i

items = {} of Int32 => Int32
n.times do
  a, b, c = (gets || "").chomp.split.map { |i| i.to_i }
  items[a] ||= 0
  items[b] ||= 0
  items[c] ||= 0
  items[a] += 1
  items[b] += 1
  items[c] += 1
end

power_up = 0
remain = 0
items.each do |_, value|
  power_up += value / 2
  remain += value % 2
end

p power_up + remain / 4