Now that's some Code.

I am seeing your comment every where , whould You explain why it would fail?

you mean it evaluates to string each loop thus having O(n^2) time complexity

bro, read clean code by Robert Cecil.
you are literally righting a spell to summon satan.

what is this 8x8 matrix ????
and why do you add 2 if start or finish is a corner

could you explaing your code to me in simple terms I really dont get what its doing or why you have -1 1 2 etc in your arrays

whats istringstream and getLine and what do they do exactly?
also whats the use of the variable Token?

I mean the best way to do it wound be O(nlog(n)) which would be a hastle to implement (or you use fancy libraries as other solutions do);

what in the absolute code is this

I am at a loss of words

Nope it gives Nan

No need to check for negatives sqrt returns -NAN for negatives square it and it gives you NAN.