#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  ;
  cin.tie(NULL);
  ;
  int n, a;
  cin >> n;
  int ar[101] = {0};
  for (int i = 0; i < n; i++) {
    cin >> a;
    ar[a]++;
  }
  int counter = 0;
  for (int i = 1; i < 101; i++) {
    counter += ar[i] / 2;
  }
  cout << counter / 2 << endl;
}
