#include <bits/stdc++.h>

using namespace std;
using ll = long long;

int main(){
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);

    int N, A, ans=0;
    cin >> N;
    map<int, int> mp;
    for (int i=0; i<N; i++){
        cin >> A;
        mp[A]++;
    }

    for (auto [x, y] : mp) ans += y/2;
    cout << ans << endl;

    return 0;
}