import java.util.Scanner
import scala.collection.mutable.ListBuffer
object no29{
    def main(args:Array[String]):Unit={
        val scan:Scanner = new Scanner(System.in)
        val list:Array[Int] = Array.fill(10)(0)
        val n:Int = scan.nextInt
        for(i <- 1 to 3*n){
            list(scan.nextInt-1)+=1
        }
        var res:Int = 0
        for(i <- 1 to 10){
            res += list(i-1)/2
            list(i-1) %= 2
        }
        println(res+list.sum/4)
    }
}