fun main(args: Array<String>) {
	val N = readLine()!!.toInt()
	val dic = mutableSetOf<Int>()
	var cnt = 0

	for (i in 0 until N) {
		val abc = readLine()!!.split(" ").map { it.toInt() }
		abc.forEach { v ->
			if (v !in dic) {
				dic.add(v)
			} else {
				cnt += 1
				dic.remove(v)
			}
		}
	}
	cnt += dic.size / 4
	println(cnt)
}