#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, x, ans;
  scanf("%d", &n);
  vector<long double> k(101, 0);
  for (int i = 0; i < n; i++) {
    scanf("%d", &x);
    k[x]++;
  }
  for (int i = 1; i <= 100; i++) ans += k[i] / 2;
  printf("%d", ans / 2);
  return 0;
}
