Initial revision
1: Regexp: a|b(d|e(g|h|i)|f)|c 2: a: Ok 3: c: Ok 4: bd: Ok 5: bf: Ok 6: beg: Ok 7: beh: Ok 8: bei: Ok 9: b: Fail 10: be: Fail 11: bi: Fail 12: f: Fail 13: ab: Fail 14: ac: Fail