#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  int n;
  cin >> n;
  map<int, int> cnt;
  rep(i, n) {
    int a;
    cin >> a;
    cnt[a]++;
  }
  int ans = 0;
  for (auto [k, v] : cnt) ans += v / 2;
  cout << ans << endl;
  return 0;
}