#include <iostream>
using namespace std;

int main() {
  int n, itm[11] = {};
  cin >> n;
  for (int i = 0; i < 3 * n; ++i) {
    int tmp;
    cin >> tmp;
    itm[tmp]++;
  }
  int res = 0;
  for (int i = 1, cnt = 0; i < 11; ++i) {
      res += itm[i] / 2;
      itm[i] %= 2 ;
      cnt += itm[i];
      if (cnt == 4) {
        cnt = 0;
        res++;
      }
  }
  cout << res << endl;
  return 0;
 }