/**
 *	yukicoder no.29
 *	@author scache
 */

object Main{
	def main(args: Array[String]){
		val sc = new java.util.Scanner(System.in)

		val n = sc.nextInt
		val items = List.fill(n*3)(sc.nextInt)

		val a = (for(item <- items.distinct) yield {
			items.filter(_==item).length/2
		}).sum

		println((items.length-a*2)/4 + a)
	}
}