#include <bits/stdc++.h>
using namespace std;
int a[10000];
int b[10000];
int res;
int n;
int main() {
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
    b[a[i]] = b[a[i]] + 1;
  }
  for (int i = 1; i <= 100; i++) {
    b[i] /= 2;
    res += b[i];
  }
  cout << res / 2;
  return 0;
}
