import java.util.*;
import java.util.stream.IntStream;
public class Main{
	static Scanner s=new Scanner(System.in);
	static int getInt(){return Integer.parseInt(s.next());}
	static IntStream REPS(int v){return IntStream.range(0,v);}
	static IntStream INS(int n) {return REPS(n).map(i->getInt());}
	public static void main(String[]$){
		HashMap<Integer,Integer>h=new HashMap<>();
		INS(getInt()*3).forEach(i->h.merge(i,1,Integer::sum));

		Collection<Integer>b=h.values();
		System.out.println(
				b.stream()
				.filter(i->i%2==1)
				.count()/4
				+b.stream()
				.mapToInt(i->i/2)
				.sum()
				);
	}
}