class Set {
    private:
        std::vector<int> _vec;
        int _evens;
    public:
        Set();
        void putIn(int e);
        void deleteItem(int e);
        bool isEmpty() const {return _vec.size == 0;};
        bool isIn(int e) const;
        int getEvens() const;
        void print() const;
        friend std::ostream& operator<< (std::ostream& s, const Set& a);
};

std::ostream& operator<< (std::ostream& s, const Set& a) {
    for(int i = 0; i < a._vec.size() - 1; i++){
        s << a._vec[i] << " ";
    }
    s << std::endl;
    return s;
}