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