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

public class Main{
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int N = scan.nextInt();
//		int []a = new int[N];
//		int []b = new int[N];
//		int []c = new int[N];
		int []x = new int[3 *N];
		for(int i = 0; i < 3 * N; i++) {
			x[i] = scan.nextInt();
		}
		scan.close();
		Arrays.sort(x);
		int temp = x[0];
		int cnt1 = 1;
		int cnt2 = 0;
		int ans = 0;
		for(int i = 1; i < 3 * N; i++) {
			if(temp == x[i]) {
				cnt1 ++;
			}else {
				ans += cnt1 / 2;
				cnt2 += cnt1 % 2;
				temp = x[i];
				cnt1 = 1;
			}
		}
		ans += cnt1 / 2;
		cnt2 += cnt1 % 2;
		ans += cnt2 / 4;
		System.out.println(ans);
	}
}