#include <iostream>
#include <vector>

using namespace std;
int main()
{
	int a,b;
	int icnt[10];
	int pcnt=0;
	vector<int> item;
	cin >> a;
	item.resize(a * 3);
	for (int i = 0; i < a * 3; i++)
	{
		cin >> b;
		item[i] = b;
	}

	for (int i = 0; i < 10; i++)
	{
		for (unsigned int j = 0; j < item.size(); j++)
		{
			if (item[j]%10 == i)
			{
				icnt[i]++;
			}
		}
	}

	for (int i = 0; i < 10; i++)
	{
		int sum = icnt[i] / 2;
		pcnt += sum;
	}

	for (int i = 0; i < 10; i++)
	{
		int ks=0;
		ks += icnt[i] % 2;
		if (ks == 4) pcnt++;
	}

	cout << pcnt << endl;
	return 0;
}