#include<iostream>

int main() {
	int n, items[10]={0};
	std::cin >> n;

	for (int i = 0; i < n * 3; i++) {
		int num;
		std::cin >> num;
		items[num - 1]++;
	}

	int powerup_count = 0;
	int d = 0;
	for (int i = 0; i < 10; i++) {
		powerup_count += items[i] / 2;
		d += items[i] % 2;
	}
	powerup_count += d / 4;
	std::cout << powerup_count << std::endl;
	return 0;
}