int path_between_two_nodes(const std::string& first, const std::string& second)
    {
        // first find both nodes
        planet* first_p = nullptr;
        planet* second_p = nullptr;

        std::stack<planet*> stack;
        for (auto& i : branches)
            stack.push(i.get());

        while (!stack.empty())
        {
            auto current_branch = stack.top();
            stack.pop();

            for (auto& i : current_branch->get_childs())
            {
                stack.push(i.get());
            }

            if (current_branch->name == first)
            {
                first_p = current_branch;
            }
            if (current_branch->name == second)
            {
                second_p = current_branch;
            }
        }
        // done
        // now find find the path to COM from both

        std::vector<planet*> first_path;
        auto temp = first_p;
        while (temp != nullptr)
        {
            first_path.push_back(temp);
            temp = temp->parent;
        }

        std::vector<planet*> second_path;
        temp = second_p;
        while (temp != nullptr)
        {
            second_path.push_back(temp);
            temp = temp->parent;
        }


        // done
        // now find the first same node

        planet* first_intersection = nullptr;

        std::reverse(first_path.begin(), first_path.end());
        std::reverse(second_path.begin(), second_path.end());


        for (auto i = first_path.begin(); i < first_path.end(); ++i)
        {
            for (auto j = second_path.begin(); j < second_path.end(); ++j)
            {
                if (*i == *j)
                    first_intersection = *i;
            }
        }

        std::reverse(first_path.begin(), first_path.end());
        std::reverse(second_path.begin(), second_path.end());

        int ctr1 = 0;
        for (auto& e : first_path)
        {
            if (e == first_intersection)
            {
                ++ctr1;
                break;
            }
            ++ctr1;
        }

        int ctr2 = 0;
        for (auto& e : second_path)
        {
            if (e == first_intersection)
            {
                ++ctr2;
                break;
            }
            ++ctr2;
        }

        std::cout << ctr1 << "  " << ctr2 << std::endl;
        return ctr1 + ctr2 - 4;
    }