#include <iostream>
#include <vector>
#include <array>
int main()
{
	int N;
	std::cin >> N;
	std::vector<int> Item;
	Item.resize(N * 3);
	for (int i = 0; i < N * 3; i++)
	{
		std::cin >> Item[i];
	}
	std::array<int, 10> ItemAll;
	for (int i = 0; i < 10; i++)
	{
		ItemAll[i] = 0;
	}
	for (int i = 0, n = (unsigned)Item.size(); i < n; i++)
	{
		ItemAll[Item[i]]++;
	}
	int PowerUp = 0;
	for (int i = 0; i < 10; i++)
	{
		while (ItemAll[i] >= 2)
		{
			PowerUp++;
			ItemAll[i] -= 2;
		}
	}
	for (int i = 1; i < 10; i++)
	{
		ItemAll[0] += ItemAll[i];
	}
	PowerUp += ItemAll[0] / 4;

	std::cout << PowerUp << std::endl;

	return 0;
}