#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <climits>
#include <numeric>
#include <iterator>
#include <cmath>
#include <set>
#include <bitset>
#include <cassert>
using namespace std;

namespace Estd {
	// return 1's position (...3210) by given bs;
	// invarient: bs.count() == 1;
	// ex: 0000100 -> 2
	template<size_t N>
	constexpr size_t position(const bitset<N> bs) {
		assert(bs.count() == 1);
		for (int i = 0; i < N; ++i) {
			if (bs[i] == 1)
				return i;
		}
		throw;
	}
};

void solve() {
	int N {};
	cin >> N;

	int cnt {0};
	bitset<10+1> bs {};
	for (int i = 0; i < 3*N; ++i) {
		int item {};
		cin >> item;
		if (bs[item]) {
			++cnt;
			bs.reset(item);	
		} else {
			bs.set(item);
		}
	}
	cnt += bs.count() / 4;
	cout << cnt << endl;
}

int main() {
	solve();
	return 0;
}