#include <bits/stdc++.h>
using namespace std;
const int N = 101;
int n, sol = 0;
unordered_map<int, int> mp;
int main() {
  scanf("%d", &n);
  for (int i = 0; i < n; i++) {
    int x;
    scanf("%d", &x);
    mp[x]++;
  }
  for (auto i = mp.begin(); i != mp.end(); i++) {
    sol += (i->second) / 2;
  }
  printf("%d", sol / 2);
  return 0;
}
