package m.shin;
import java.util.Scanner;
public class Con29 {

	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		int N = s.nextInt() , count = 0;
		int[] item = new int[10];
		for(int i = 0;i < 3*N;i++){
			int k = s.nextInt();
			item[k-1]++;
			if(item[k-1] == 2){
				count++;
				item[k-1] = 0;
			}
		}
		s.close();

		N = 0;
		for(int i = 0;i < 10;i++){
			N += item[i];
		}
		System.out.println(count + N / 4);

	}

}