class Solution {
public:
    int distributeCandies(vector<int>& candies) {

        int max_candies = candies.size() / 2;

        //The length of the given array is in range [2, 10,000], and will be even.
        if (max_candies < 1 || max_candies > 5000 || candies.size() % 2) {
            return 0;
        }

        map<int,char> max_uniq;
        for(auto candy: candies) {
            //The number in given array is in range [-100,000, 100,000].
            if (candy < -100000 || candy > 100000) return 0;
            max_uniq[candy] = '1';
        }

        return ((int) max_uniq.size() < max_candies) ? max_uniq.size() : max_candies;
    }
};