Enter a regexp that matches all the items in the first column (positive examples) but none of those in the second (negative examples). When you press "submit", you will see what matched.

Positive	Negative
affgfking rafgkahe bafghk baffgkit affgfking rafgkahe bafghk baffg kit	fgok a fgk affgm afffhk fgok afg.K aff gm afffhgk