#include <bits/stdc++.h>
using namespace std;
struct Pt {
  int x, y;
};
Pt pt[10000];
int a[101] = {0};
void init() {}
int main() {
  init();
  int n, x, R = 0;
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> x;
    a[x]++;
  }
  for (int i = 1; i <= 100; i++)
    if (a[i] / 2 > 0) R += a[i] / 2;
  cout << R / 2;
  return 0;
}
