#include <bits/stdc++.h>
using namespace std;
vector<int> v;
int a[101];
int s, i, j, r, n, l = 0;
int main() {
  scanf("%d", &n);
  for (i = 1; i <= n; i++) scanf("%d", &a[i]);
  for (i = 1; i <= n; i++) {
    s = 1;
    for (j = i + 1; j <= n; j++)
      if (a[i] == a[j] && a[i] != -1) {
        s++;
        a[j] = -1;
      }
    if (s % 2 == 1)
      l = l + s - 1;
    else
      l = l + s;
  }
  printf("%d", l / 4);
}
