#include <bits/stdc++.h>
using namespace std;
int main() {
  int s = 0, n, a[11111], k, mp[11111];
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    mp[a[i]]++;
  }
  for (int i = 0; i < n; i++) {
    s += mp[a[i]] / 2;
    mp[a[i]] = 0;
  }
  cout << s / 2;
}
