#include <bits/stdc++.h>
using namespace std;
const long long int MOD = 1e9 + 7;
const int mxN = 1000005;
int dx[4] = {0, 0, 1, -1};
int dy[4] = {1, -1, 0, 0};
int kx[8] = {2, 1, -1, -2, -2, -1, 1, 2};
int ky[8] = {1, 2, 2, 1, -1, -2, -2, -1};
long long int qpow(unsigned long long x, int y, int p) {
  long long int res = 1;
  x = x % p;
  while (y > 0) {
    if (y % 2 == 1) res = (res * x) % p;
    y = y / 2;
    x = (x * x) % p;
  }
  return res;
}
long long int modInverse(unsigned long long x, int p) {
  return qpow(x, p - 2, p);
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n;
  cin >> n;
  set<int> st;
  map<int, int> mp;
  for (int i = 0; i < n; i++) {
    int a;
    cin >> a;
    mp[a]++;
  }
  int total = 0;
  for (auto i : mp) {
    total += i.second / 2;
  }
  cout << total / 2 << endl;
}
