// No.29 パワーアップ
// https://yukicoder.me/problems/no/29
//

#include <iostream>
#include <unordered_map>
using namespace std;

int solve(unordered_map<int, int>& items);


int main() {
    unsigned int N;
    cin >> N;

    unordered_map<int, int> items;
    int t;
    for (auto i = 0; i < 3*N; i++) {
        cin >> t;
        items[t]++;
    }

    int ans = solve(items);
    cout << ans << endl;
}

int solve(unordered_map<int, int>& items) {
    int power_up = 0;
    int remaining = 0;
    for (auto i: items) {
        if (i.second % 2 == 1)
            remaining++;
        power_up += (i.second / 2);
    }
    power_up += (remaining / 4);
    return power_up;
}