Fifteen for zero
I have a sneaking suspicion that there's no such creature -- and boy, if there were, I'd buy one!! Consider the grammar check facility on Microsoft. It's so dumb that any of the teachers on this site could out-grammar-check it if they . . . had nothing better to do with their lives.
Language is evilly complex -- that's what makes a site like this so groovy: only those humans are clever enough to get language right.
I'll be pleased to hear how you fare.