#include <bits/stdc++.h>
using namespace std;
const int Max = 2e6 + 10;
const int Mod = 1e9 + 7;
bool compare(const pair<int, int> &a, const pair<int, int> &b) {
  return (a.first > b.first);
}
int main() {
  (ios_base::sync_with_stdio(false), cin.tie(NULL));
  ;
  int n;
  cin >> n;
  int ara[n + 1];
  int i;
  int bra[110] = {0};
  for (i = 0; i < n; i++) {
    cin >> ara[i];
    bra[ara[i]] += 1;
  }
  int t = 0;
  for (i = 0; i <= 100; i++) {
    t += bra[i] / 2;
  }
  cout << t / 2 << endl;
}
