import java.util.Arrays;
import java.util.Scanner;

public class Yukicoder29 {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int[] item = new int[10];

		Arrays.fill(item, 0);
		for (int i = 0; i < n * 3; i++) {
			item[sc.nextInt() - 1]++;
		}

		int res = 0, other = 0;
		for (int i = 0; i < 10; i++) {
			if (item[i] >= 2) {
				res += item[i] / 2;
			}
			other += item[i] % 2;
		}
		System.out.println(res + other / 4);
	}
}