#include <bits/stdc++.h>   using namespace std;   int main() {     int n, sti[101], i, x, ans;     cin >> n;     memset(sti, 0, sizeof(sti));     for (i = 1; i <= n; i++) {       cin >> x;       sti[x]++;     }     ans = 0;     for (i = 1; i <= 100; i++) {       ans += 2 * (sti[i] / 4);       sti[i] %= 4;       ans += sti[i] / 2;     }     cout << ans / 2 << endl;     return 0;   }   