int sockMerchant(int n, vector<int> ar) {
    unordered_map<int, int> hashmap;
    
    for (int num : ar) {
        hashmap[num]++;
    }
    
    int total = 0;
    for (auto [num, count]: hashmap) {
        total += count / 2;
    }
    
    return total;
}