import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

public class No029_PowerUp {

	public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();	// 戦闘回数
        
        List<Integer> list = new ArrayList<Integer>();
        for (int i=0; i<a*3; i++) {
    		list.add(sc.nextInt());
        }

        Collections.sort(list);
        
        int pairItem = 0;
        int noPairItem = 0;
        
        for (int i=0;i<list.size()-1;i++) {
        	if (list.get(i) == list.get(i+1)) {
        		pairItem++;
        		i++;
        	} else if(list.get(i) != list.get(i+1)) {
        		noPairItem++;
        		if (i == list.size()-1) {
            		noPairItem++;
        		}
        	}
        }
        int result = pairItem + (noPairItem / 4);
        System.out.println(result);
	}

}