#include <bits/stdc++.h>
int main() {
  int n, k, a[300], s[300], sum = 0;
  scanf("%d", &n);
  for (int i = 1; i < 101; i++) {
    s[i] = 0;
  }
  for (int i = 1; i < n + 1; i++) {
    scanf("%d", &a[i]);
    s[a[i]]++;
  }
  for (int i = 1; i < 101; i++) {
    sum += s[i] / 2;
  }
  printf("%d", sum / 2);
}
