#include <bits/stdc++.h>
using namespace std;
const int N = 1e6 + 6, nBits = 2e8 + 5, MM = (1 << 16), MAX = 1111,
          OO = 0x3f3f3f3f, MOD = 1e9 + 7, inf = 1 << 30;
const long long INF = (long long)1e18;
long long GCD(long long a, long long b) { return !b ? a : GCD(b, a % b); }
long long LCM(long long x, long long y) { return (x * y / GCD(x, y)); }
long long fact(long long z) { return (z <= 1) ? 1 : z * fact(z - 1); }
int n, x, A[111], sum, freq[111];
map<int, int> mp;
vector<int> v;
int main() {
  scanf("%d", &n);
  for (int i = 0; i < n; ++i) {
    scanf("%d", &x);
    A[i] = x;
    if (!freq[x]) v.push_back(x);
    ++freq[x];
  }
  for (int i = 0; i < v.size(); ++i)
    sum += freq[v[i]] & 1 ? freq[v[i]] - 1 : freq[v[i]];
  printf("%d\n", sum / 4);
  return 0;
}
