// Created on iPad.
#include <iostream>
#include <cstdio>
#include <cstring>
#include <map>
#include <vector>
#include <algorithm>

using namespace std;

const int N = 1e6 + 10;

int mp[N];
int n;
void solve() {
    cin >> n;
    for (int i = 1; i <= n; i++) {
        int x;
        cin >> x;
        mp[x]++;
    }
    int res = 0;
    for (int i = 1; i <= N; i++) res += mp[i] / 2;
    cout << res << endl;
    return;
}

int main() {
    int T = 1;
    // cin >> T;
    while (T--) {
        solve();
    }
    return 0;
}