The problem calls for us to maintain two parallel symbols in a string, so we'll need some way to keep track of the "balancing".

This means we'll need a certain technique which allows for keeping score of both of the following things:

1. We should track what's "coming in" or incoming.
2. We should also keep count of what's "going out" or outgoing.

Let's start to brainstorm ways of keeping that information handy and accessible.