#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <utility>
#include <iomanip>
#include <cmath>
using namespace std;
#define diff(x, y) ((x) > (y) ? ((x) - (y)) : ((y) - (x)))

int main(void) {
	int n, no, ans = 0, sum = 0;
	cin >> n;
	vector <int> x(11, 0);
	for (int i = 0; i < n * 3; i++) {
		sum++;
		cin >> no;
		x[no]++;
		if (x[no] >= 2) {
			ans++;
			sum -= 2;
			x[no] -= 2;
		}
	}
	cout << ans + sum / 4<< endl;
	return 0;
}