#, aac, acc, abc, ac, abbc, abbbc, abbbbc, aabc, aabbc
a.c
a[ab]c
a[^ab]c
ab*c
a.b{2,4}c

aac, abc, acc
aac, abc
асс
ac, abc, abbc, abbbc, abbbbc
aabbc, abbbc, abbbbc