#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <utility>

using namespace std;

int main() {
	int n, a;
	int item[11] = {};

	cin >> n;
	for (int i = 0; i < 3 * n; i++) {
		cin >> a;
		item[a]++;
	}
	int count = 0;
	int rest = 0;
	for (int i = 1; i <= 10; i++) {
		count += item[i] / 2;
		rest += item[i] % 2;
	}
	count += rest / 4;
	cout << count << endl;
	return 0;
}