#include <iostream>

using namespace std;

int main() {
    int n, level = 0;
    int items[10];
    cin >> n;
    for (int i = 0; i < 10; i++) {
        items[i] = 0;
    }

    for (int i = 0; i < n; i++) {
        for (int j = 0; j< 3; j++) {
            int tmp;
            cin >> tmp;
            tmp -= 1;
            items[tmp]++;
            if (items[tmp] == 2) {
                level++;
                items[tmp] = 0;
            }
        }
    }

    int leftover = 0;
    for (int i = 0; i < 10; i++) {
        leftover += items[i];
    }
    level += leftover / 4;
    cout << level << endl;

    return 0;
}