import java.util.Scanner;

public class Test {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int[] t = new int[10];
		int n = sc.nextInt() * 3, cnt = 0;
		for (int i = 0; i < n; i++) {
			t[sc.nextInt() - 1]++;
		}
		for (int i = 0; i < 10; i++) {
			while (t[i] >= 2) {
				cnt++;
				n -= 2;
				t[i] -= 2;
			}
		}
		cnt += n / 4;
		System.out.println(cnt);
	}
}