#include <bits/stdc++.h>
using namespace std;
string toString(int n) {
  ostringstream ost;
  ost << n;
  ost.flush();
  return ost.str();
}
int toInt(string s) {
  int r = 0;
  istringstream sin(s);
  sin >> r;
  return r;
}
int main() {
  int n;
  cin >> n;
  int arr[100];
  map<int, int> mp;
  vector<int> vp;
  for (int i = 0; i < n; i++) cin >> arr[i], mp[arr[i]]++, vp.push_back(arr[i]);
  sort(arr, arr + n);
  {
    sort((vp).begin(), (vp).end());
    (vp).erase(unique((vp).begin(), (vp).end()), vp.end());
  };
  int ans = 0;
  for (int i = 0; i < vp.size(); i++) {
    ans += mp[vp[i]] / 2;
  }
  cout << (ans / 2) << endl;
  return 0;
}
