#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  int num[105];
  int a;
  while (cin >> n) {
    memset(num, 0, sizeof(num));
    for (int i = 0; i < n; i++) {
      cin >> a;
      num[a]++;
    }
    int sum = 0;
    for (int i = 1; i <= 100; i++) {
      sum += num[i] / 2;
    }
    cout << sum / 2 << endl;
  }
  return 0;
}
