package main

import . "fmt"

func main() {
	var n,a,b,c int
	Scan(&n)
	var t [11]int
	for ;n>0;n-- {
		Scan(&a,&b,&c)
		t[a]++
		t[b]++
		t[c]++
	}
	for _,v:=range t[:] {
		n+=v/2
		t[0]+=v%2
	}
	Println(n+t[0]/4)
}