#include <bits/stdc++.h>
using namespace std;
const int maxx = 110;
int a[maxx] = {0};
int main() {
  int n, i, sum, m;
  while (cin >> n) {
    memset(a, 0, sizeof(a));
    for (i = 1; i <= n; i++) {
      cin >> m;
      a[m]++;
    }
    sum = 0;
    for (i = 1; i <= 110; i++) sum = a[i] / 2 + sum;
    sum = sum / 2;
    cout << sum << endl;
  }
  return 0;
}
