n = gets.to_i
arr = Array.new(11, 0)
ans = 0

n.times do |i|
    a, b, c = gets.split.map(&:to_i)
    arr[a] += 1
    arr[b] += 1
    arr[c] += 1
end

10.times do |j|
    j += 1
    x, y = arr[j].divmod(2)
    ans += x
    arr[j] = y
end
puts ans + arr.sum / 4