#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  int n;
  while (cin >> n) {
    vector<int> a(101, 0);
    for (int i = (0); i < ((n)); ++i) {
      int t;
      cin >> t;
      a[t]++;
    }
    int res = 0;
    for (int i = (0); i < ((101)); ++i) res += a[i] / 2;
    res /= 2;
    printf("%d\n", res);
  }
  return 0;
}
