public static int sockMerchant(int n, List<Integer> ar) {
    // Write your code here
        int count = 0;
        HashMap<Integer, Integer> hMap = new HashMap<>();
        for(Integer ele : ar){
            if(hMap.containsKey(ele)){
                int freq = hMap.get(ele);
                freq++;
                hMap.put(ele, freq);
                if(freq % 2 ==0)
                    count++;
            }else{
                hMap.put(ele, 1);
            }
        }
        return count;
    }

int sockMerchant(int n, vector<int> ar) {
    int count = 0;
    map<int,int>mp;
    for(int i=0;i<n;i++){
    mp[ar[i]]++;
    }
    for(auto it:mp){
        if(it.second > 1){
            count+= it.second/2;
        }
    }
    return count;
}

    public static int sockMerchant(int n, List<Integer> ar) {
    // Write your code here
        int count = 0;
        HashMap<Integer, Integer> map = new HashMap<>();

        for (Integer i : ar) {
            if (!map.containsKey(i))
                map.put(i, 1);
            else {
                map.put(i, map.get(i) + 1);

                if (map.get(i) % 2 == 0)
                    count++;
            }
        }
        return count;

    }

int sockMerchant(int n, int* ar) {
    int * socks = calloc(2,sizeof(int)); int ssize = 2;
    *socks = *ar;
    for(int i = 0; i < n; i++){
        bool found = false;
        for(int j = 0; j < ssize; j+=2){
            if(ar[i] == socks[j]){
                socks[j+1]++; found = true;
                break;
            }
        }
        if(!found){ ssize+=2;
            socks = realloc(socks,ssize*sizeof(int));
            socks[ssize-2] = ar[i]; socks[ssize-1] = 1;
        }
    }
    int pairs = 0;
    for(int i = 1; i < ssize;i+=2){
        pairs+=socks[i]/2;
    }
    return pairs;
}

public static int sockMerchant(int n, List<int> ar)
    {
        if(ar.Count() == 1) return 0;
              
        ar.Sort();
        var pairs = 0;
        var i = 0;
        
        while(ar.Count() != 0){
            if(ar.Count() == 1)
                break;
            else if(ar[i] == ar[i + 1]) {
                ++pairs;
                ar.RemoveRange(0, 2);
                i = 0;
            }
            else
                ar.RemoveAt(i);    
        }
        
        return pairs;
    }