#include <bits/stdc++.h>
int main() {
  int n;
  while (scanf("%d", &n) == 1) {
    int b, a[105] = {0}, i;
    for (i = 1; i <= n; i++) {
      scanf("%d", &b);
      a[b]++;
    }
    int sum = 0;
    for (i = 1; i <= 100; i++)
      if (a[i] > 1) sum += a[i] / 2;
    printf("%d\n", sum / 2);
  }
  return 0;
}
