I'm in the same position mad max !
I have presumed that we have to mark out a red "A" as the Scarlet Letter (meaning adultress in the Nathaniel Hawthorne book). But of the 22 As in the grid I cannot make 12 of them make such a letter without it having curved sides, and them not being equally spaced out.
Perhaps someone else may have a suggestion.
(I have just posted this question myself at 19.10 but did not see your query -- but somehow my question hasn't appeared anyway ! And I thought that this site had started to behave itself !!)