#include <bits/stdc++.h>
using namespace std;
int main() {
  int a[200], n, k;
  for (int i = 0; i <= 200; i++) a[i] = 0;
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> k;
    a[k]++;
  }
  int kol = 0;
  for (int i = 1; i <= 198; i++) kol += a[i] / 2;
  cout << kol / 2;
  return 0;
}
