#include <cstdio>
#include <algorithm>
#include <numeric>
#include <vector>

int main() {
  size_t n;
  scanf("%zu", &n);
  n *= 3;

  std::vector<int> a(11, 0);
  for (size_t i = 0; i < n; ++i) {
    size_t j;
    scanf("%zu", &j);
    ++a[j];
  }

  int res = 0;
  for (auto& ai: a) {
    res += ai / 2;
    ai %= 2;
  }

  res += std::accumulate(a.begin(), a.end(), 0) / 4;
  printf("%d\n", res);
}