template<typename T, std::size_t max_size_>
class safe_static_vector {
    T arr_[max_size_];
    std::atomic<std::size_t> current_size_ = 0;

public:
    T& operator[](std::size_t i) {
        return arr_[i];
    }

    void push_back(T t) {
        ++current_size;
        arr_[current_size_-1] = t;
    }
};