#include <bits/stdc++.h>
using namespace std;
long long sum;
int ans[200];
bool vis[200];
bool Judge(int a, int b, int c, int d) {
  if (a == b && c == d)
    return true;
  else if (a == c && b == d)
    return true;
  else if (a == d && b == c)
    return true;
  return false;
}
int main() {
  int n;
  while (scanf("%d", &n) != EOF) {
    sum = 0;
    memset(vis, false, sizeof vis);
    for (int i = 1; i <= n; i++) scanf("%d", &ans[i]);
    for (int i = 1; i <= n; i++) {
      for (int j = i + 1; j <= n; j++) {
        for (int k = j + 1; k <= n; k++) {
          for (int top = k + 1; top <= n; top++) {
            if (vis[i] || vis[j] || vis[k] || vis[top]) continue;
            if (Judge(ans[i], ans[j], ans[k], ans[top])) {
              vis[i] = vis[j] = vis[k] = vis[top] = true;
              sum++;
            }
          }
        }
      }
    }
    printf("%lld\n", sum);
  }
  return 0;
}
