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

int main() {
    int N;
    int cnt[11] = {};
    cin >> N;
    N *= 3;
    while (N--) {
        int a;
        cin >> a;
        cnt[a]++;
    }
    int ans = 0, tmp = 0;
    for (int i = 0; i <= 10; i++) {
        ans += cnt[i] / 2;
        tmp += cnt[i] % 2;
    }
    ans += tmp / 4;
    cout << ans << endl;
}