Shortening codes

This is a regex golf problem. You have to write a regex that matches all lines from one list and none from the second one. Matching is implemented as Perl's m//, so it's not a precise match. E.g. to match "SPOJ" you don't need regex /^SPOJ$/ since it's enough to write /PO/ or /J/.

The regexes submitted should be compatible with Perl regular expressions (version 5.20.1).

Score is calculated as follows: it's equal to the length of your regex and for every line from the first list that's not matched by your regex X points are added to your score. Analogically, for every line from the second list that's matched by your regex X points are added to your score. The lower your score is, the better. X often equals 10 but it's different in some problems. Check below this problem's X value.

To quickly check the quality of your solution visit the original regex golf project.

Please don't look for solutions for this problem online or at least don't post them here if you didn't come up with them on your own.

Match all of these...

• aerate aerate arrest errant serene tanner testes
• aerate assent assent assert rester retest tenant
• aerate assert rearer renter resent serene teaser
• aerate easter easter tenant tester testes tsetse
• arrest arrest easter entree errant resent senate
• assent assess assets estate resent staree teaser
• assert astern renter rerent resent staree street
• assert enseat entree errata rennet teaser tsetse
• assert rennet renter reseat rester serene tenant
• assess easter estate rennet rennet tenant testes
• assess easter estate rerent resent retest snarer
• assess renter renter searer seater snarer testes
• astern enseat entree serene staree tartar tartar
• astern rennet retest searer snarer tartar tester
• enseat errata seater senate strata teaser tsetse
• entree searer staree taster taster tenant testes
• rerent rester tanner tartar teaser teaser testes

And none of these...

• aerate astern assess enseat senate street tsetse
• aerate rennet errant enseat rerent senate testes
• arrest assess assess assent astern searer testes
• assert assess errata enseat earner seater serene
• assert astern staree senate snarer tanner tester
• assert strata rerent rerent tanner testes tsetse
• assess easter entree rester reseat seater tartar
• astern assets rearer rearer assess rearer testes
• astern easter taster serene reseat taster tester
• earner entree rerent reseat teaser strata staree
• earner errant estate taster reseat estate taster
• enseat astern arrest enseat searer seater tenant
• errant errant senate renter rearer street tsetse
• rennet rennet assent errant rester staree tester
• rennet snarer senate retest tanner tartar tsetse
• retest astern arrest tsetse strata senate tsetse
• searer errant teaser staree assess teaser tsetse

X = 20