#include <bits/stdc++.h>
using namespace std;
int num[110], mark[110];
int main() {
  int n, i, temp, ans;
  while (cin >> n) {
    memset(mark, 0, sizeof(mark));
    for (i = 0; i < n; i++) {
      cin >> num[i];
      mark[num[i]]++;
    }
    ans = 0;
    for (i = 1; i <= 100; i++) {
      temp = mark[i] / 2;
      ans += temp;
    }
    cout << ans / 2 << endl;
  }
  return 0;
}
