#include <bits/stdc++.h>
using namespace std;
bool f = 0;
void first() {
  long long n, c = 0;
  cin >> n;
  long long a[n];
  for (long long i = 0; i < n; i++) cin >> a[i];
  sort(a, a + n);
  for (long long i = 1; i < n; i++) {
    if (a[i] == a[i - 1]) c++, i++;
  }
  cout << c / 2 << '\n';
  return;
}
int main() {
  ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
  srand(time(NULL));
  long long t = 1, test = 0;
  while (t--) {
    first();
  }
}
