#include <iostream>
using namespace std;

int main() {
    int n;
    int cards[10] = {};
    cin >> n;
    for (int i = 0; i < 3 * n; i++) {
        int x;
        cin >> x;
        cards[x-1]++;
    }
    int ans = 0, rest = 0;
    for (int i = 0; i < 10; i++) {
        ans += cards[i] / 2;
        rest += cards[i] % 2;
    }
    ans += rest / 4;
    cout << ans << endl;
    return 0;
}