n = gets.chomp.to_i
items = []
n.times do
  gets.split.map(&:to_i).each do |i|
    items << i
  end
end
items.sort!

flags = Array.new(n * 3){ false }
count = 0
prev = items[0]
1.upto(n * 3) do |i|
  if prev == items[i] && !flags[i-1] && !flags[i]
    count += 1
    flags[i-1] = true
    flags[i]   = true
  end
  prev = items[i]
end

count += flags.select{|i| !i}.size/4
puts count