#include <bits/stdc++.h>
using namespace std;

int main() {
    int n;
    cin >> n;
    vector<int> items(10);
    for (int i = 0; i < 3 * n; i++) {
        int a;
        cin >> a;
        items.at(a - 1)++;
    }
    int ans = 0, odd = 0;
    for (int i = 0; i < 10; i++) {
        ans += items.at(i) / 2;
        odd += items.at(i) % 2;
    }
    ans += odd / 4;
    cout << ans << endl;
}