This seems like it shouldn't be terribly difficult to implement, but, I can't make any sense of what is actually being asked. I'm trying to follow the "let's take a walk" examples as well, but to no avail.

If there have been no left choices, l = 1. Why isn't it 0 since left has been chosen 0 times so far?

If there have been no right choices, r = 0. Okay maybe that makes sense, as right has been chosen 0 times. But then why is s = 1 instead of 0? Or, why is m = 0 instead of 1? What do m and s even represent?

Since they say that the word "and" may or may not come in between numbers, couldn't you just replace all the "and"s with before digging in?