#include <iostream>
int N, a, b, c, x, y, i = 11, I[11];
int main() {
  std::cin >> N;
  while (N-- && std::cin >> a >> b >> c) I[a]++, I[b]++, I[c]++;
  while (i--) x += I[i] / 2, y += I[i] % 2;
  std::cout << x + y / 4 << "\n";
}