n = gets.to_i
items = Array.new(n * 3)

n.times do | i |
    items[3 * i], items[3 * i + 1], items[3 * i + 2] = gets.split.map(&:to_i)
end

items.sort!()
powerup_count = 0
tmp = -1

items.length.times do | j |
    if j == 0
        tmp = items[j]
        next
    end
    if tmp == items[j]
        items[j] = '*'
        items[j - 1] = '*'
        powerup_count += 1
        tmp = -1
    else
        tmp = items[j]
    end
end

items.delete('*')
p powerup_count += items.length / 4