#include <bits/stdc++.h>
using namespace std;
bool cprime(int x) {
  if (x == 1) return false;
  if (x <= 3) return true;
  if (x % 2 == 0 || x % 3 == 0) return false;
  for (int i = 5; i <= sqrt(x); i += 6)
    if (x % i == 0 || x % (i + 2) == 0) return false;
  return true;
}
bool cpalin(string s) {
  int n = s.length(), l;
  if (n == 1) return true;
  if (n % 2 == 0)
    l = n / 2 - 1;
  else
    l = (n - 1) / 2 - 1;
  for (int i = 0; i <= l; i++)
    if (s[i] != s[n - i - 1]) return false;
  return true;
}
void sieveOfEratosthenes(int n) {
  bool arr[n + 1];
  for (long long(i) = 0; i < n + 1; i++) arr[i] = true;
  for (int i = 2; i * i <= n; i++) {
    if (arr[i] == true) {
      for (int j = i * i; j <= n; j += i) {
        if (arr[j] == true) arr[j] = false;
      }
    }
  }
}
long long ndivs(long long n) {
  int N = 100;
  bool arr[N];
  for (long long(i) = 0; i < N; i++) arr[i] = true;
  for (int i = 2; i * i <= N; i++) {
    if (arr[i] == true) {
      for (int j = i * i; j <= N; j += i) {
        if (arr[j] == true) arr[j] = false;
      }
    }
  }
  long long p = 1;
  for (long long(i) = 2; i < N; i++) {
    if (arr[i] == true && n % i == 0) {
      long long m = 0;
      long long cp = n;
      while (cp % i == 0) {
        cp /= i;
        m++;
      }
      p *= (m + 1);
    }
  }
  return p;
}
bool compare(int a, int b) { return a > b; }
int main() {
  int n;
  cin >> n;
  int count[101] = {0};
  int arr[n];
  for (long long(i) = 0; i < n; i++) {
    cin >> arr[i];
    count[arr[i]]++;
  }
  int c = 0;
  for (long long(i) = 0; i < 101; i++)
    if (count[i] >= 4) {
      c += count[i] / 4;
      count[i] %= 4;
    }
  int p = 0;
  for (long long(i) = 0; i < 101; i++) {
    if (count[i] >= 2) p++;
  }
  if (p % 2 == 0)
    cout << c + p / 2;
  else
    cout << c + (p - 1) / 2;
  return 0;
}
