#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <utility>
#include <string>
#include <queue>
#include <stack>
#include <unordered_set>
#include <unordered_map>

using namespace std;

typedef long long int ll;
typedef pair<int, int> Pii;

const ll mod = 998244353;

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);

  int n;
  cin >> n;
  vector<int> a(n);
  for (auto &x: a) cin >> x;

  unordered_map<int, int> item_counts;
  for (auto &x: a) {
    item_counts[x]++;
  }

  int ans = 0;
  for (auto &[k, v]: item_counts) {
    ans += v / 2;
  }

  cout << ans << endl;

  return 0;
}