#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, a[100], i, num = 0, num1 = 0, num2 = 0, count = 1, j;
  cin >> n;
  for (i = 0; i < n; i++) cin >> a[i];
  for (i = 0; i < n - 1; i++) {
    count = 1;
    for (j = i + 1; j < n; j++) {
      if (a[i] == a[j] && a[j] != 0) {
        a[j] = 0;
        count++;
      }
    }
    if (count >= 4) {
      num = count / 4;
      if (num >= 1) {
        num1 += num;
        if (count % 4 >= 2) {
          num2++;
        }
      }
    } else {
      num = count / 2;
      if (num >= 1) {
        num2 += num;
      }
    }
  }
  num2 = num2 / 2;
  count = num1 + num2;
  cout << count << endl;
  return 0;
}
