1  Regexp: ((a|b|c)def)
 2  adef: Ok
 3  bdef: Ok
 4  adefg: Fail
 5  aaef: Fail
 6  Regexp: ((a|b|c|d|e|f)?(g|h|i)+(k|l)*)
 7  g: Ok
 8  gi: Ok
 9  fil: Ok
10  gikl: Ok
11  cghhhiill: Ok
12  ak: Fail