found opposite of pattern of Xs

[Stews]

hi excelers,
I need a function to find the opposite of a pattern of Xs, from a list of 30 Xs patterns (see attachment)...
thus x-x-x should result in 3 below etc run on 30 Xs.

1 x-x-x
2 xx--
3 -x-x-

any help would be greatful, thanks