void add_element(const int& element)
{
    //int* newBuffer = new int;
    //*newBuffer = element;
    //memcpy(buffer, newBuffer, sizeof (newBuffer));
    int *newBuffer = new int[capacity + 1];
    for (int i = 0; i < capacity; i++) {
        newBuffer[i] = buffer[i];
    }
    delete[] buffer;
    newBuffer[capacity] = element;
    int *buffer1 = newBuffer;
}

const int& get_element(const unsigned& index) {
    int *buffer1 = newBuffer;
    if (index < 0 || index > capacity) {
        throw std::runtime_error("index is invalid");
    }
    else {
        return buffer1[index];
    }
}