#include <bits/stdc++.h>
using namespace std;

int main() {
    int n;
    cin >> n;
    vector<int> cnt(200010);
    for (int i = 0; i < n; i++) {
        int a;
        cin >> a;
        cnt[a]++;
    }
    int ans = 0;
    for (int x : cnt) {
        ans += x / 2;
    }
    cout << ans << endl;
}