#include <iostream>
using namespace std;

int main(void) {
    int N;
    cin >> N;
    int items[10] = {0};
    for (int i = 0; i < N * 3; i++) {
        int item;
        cin >> item;
        items[item-1]++;
    }
    int level_up = 0;
    for (int i = 0; i < 10; i++) {
        level_up += items[i] / 2;
    }
    level_up += (N * 3 - level_up * 2) / 4;
    cout << level_up << endl;
    
    return 0;
}