#include <bits/stdc++.h>
#ifdef DEBUG
#include "cpp-dump/dump.hpp"
#define dump(...) cpp_dump(__VA_ARGS__)
#else
#define dump(...)
#endif
using namespace std;
typedef long long ll;

void solve() {
    ll n;
    cin >> n;
    vector<ll> A(n);
    for (ll i = 0; i < n; ++i) cin >> A[i];

    map<ll,ll> mp;
    for (ll i = 0; i < n; ++i) mp[A[i]]++;

    ll ans = 0;

    for (auto m : mp) {
        ans += m.second / 2;
    }

    cout << ans << endl;
}

int main() {
    solve();
    return 0;
}