#include <bits/stdc++.h>
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 1;
}