#include <bits/stdc++.h>

#define int long long

#define endl '\n'

#define ULL unsigned long long

#define rep(i, l, b) for (int i = l; i <= b; i++)

#define lep(i, b, l) for (int i = b; i >= l; i--)


const int N = 2e5 + 10, INF = 0x3f3f3f3f3f3f, MOD = 1e7 + 7, B = 13331;

using namespace std;

int n, m;
int a[N], b[N];
map<int, int> mp;

void solve() {
    int res = 0;
    cin >> n;
    rep(i, 1, n) {
        int x;
        cin >> x;
        mp[x]++;
    }

    for (auto x : mp) {
        res += (x.second / 2);
    }

    cout << res;
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int _ = 1;
    // cin >> _;
    while (_--) {
        solve();
    }

    return 0;
}