#include <bits/stdc++.h>
using namespace std;
int a[101] = {};
int main() {
  int n;
  cin >> n;
  for (int i = 0; i < n; i++) {
    int x;
    cin >> x;
    a[x]++;
  }
  int s = 0;
  for (int i = 1; i <= 100; i++) s += a[i] / 2;
  cout << s / 2;
  return 0;
}
