#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <list>
#include <set>
#include <unordered_set>
#include <map>
#include <unordered_map>
#include <cmath>
#include <utility>
#include <sstream>
#include <queue>
#include <queue>

using namespace std;

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);

  map<int, int> counts;
  int n;
  cin >> n;
  for (int i = 0; i < n; ++i) {
    int v;
    cin >> v;
    counts[v]++;
  }

  int sum = 0;
  for (const auto &el: counts) {
    sum += el.second / 2;
  }
  cout << sum << endl;

  return 0;
}