#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int INF = 1e9 + 10;
const ll INFL = 4e18;

int main() {
    int N;
    cin >> N;
    vector<int> cn(N + 1);
    for (int i = 0; i < N; i++) {
        int a;
        cin >> a;
        cn[a]++;
    }

    int ans = 0;
    for (int i = 1; i <= N; i++) {
        ans += cn[i] / 2;
    }

    cout << ans << endl;
}