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