func main()
	var items: []int :: #[11]int
	var N: int :: cui@input().toInt(&)
	for(1, N)
		var _: [][]char :: cui@input().split(" ")
		for i(0, 2)
			do items[_[i].toInt(&)] :+ 1
		end for
	end for
	
	var remains: int
	var ans: int
	for i(1, 10)
		do remains :+ items[i] % 2
		do ans :+ items[i] / 2
	end for
	do ans :+ remains / 4
	do cui@print("\{ans}\n")
end func