#include <bits/stdc++.h>
using namespace std;
int arr[150];
int main() {
  int n, k, i, j, ans = 0, curr, temp;
  scanf("%d", &n);
  for (i = 0; i < n; i++) {
    scanf("%d", &curr);
    arr[curr]++;
  }
  for (i = 1; i <= 100; i++) {
    ans += (arr[i] / 2);
  }
  ans /= 2;
  printf("%d\n", ans);
  return 0;
}
