a-ak a-ok aaaa aaab aaaf aaba aabb aafa aafb aaff aaka aaoo abaa abab abaf abak abb- abba abbb abbo abff aboa abob abof abok aboo afaa afak afao affa affo afka afoa afoo akaa akao akka akko akok aoba baaa baaf baak baba babb babo baff bafo bak- baka bako bbbb boab boak boba bobb bobo bofa boff boka boko boob boof book f--k faaa faba fabo fafa faff fafo fako ffff fkab foaf foak foba fofo foof fook kaaa kaab kaaf kaak kaba kabb kabf kabo kafa kaff kaka kakk kako kaoa kaok kbaa kbab kbak kbba kbbb kbbf kbbk kbbo kbfb kbff kbfk kbfo kbkb kbkf kbkk kbko kboa kbob kbok kboo kfab kfbk kffa kffb kfff kffk kfka kfkb kfok kfoo kkaa kkba kkbb kkbo kkkk kkoa kkob kkoo koab koak koba kobb kobk kobo kofa koff kofk kofo koka kokb kokf kokk koko koob kook kooo oafo obak obba obbo obkb obok off- offa offo okak okka okko okok ooaa ooak ooba ooff oooo