I would recommend you to look at the systems expressions, they really have useful stuff.
What you are looking for is right(word,1)
this would give you the last character of a string.
If you put another number instead of 1, it would give you the right most X characters of the string, This would be useful if you want to give more hints later on.
You could just set a text object to that to show the hint, hope this helps!