a-a a-b a-c aaa aab aac aaj aak aao ab- aba abb abc abj abk abo ac- aca acb acc acj ack aco aja ajb ajc ajj ajk ajo aka akb akc akj akk ako aoa aob aoc aoj aok aoo baa bab bac baj bak bao bba bbb bbc bbk bbo bca bcb bcc bcj bck bco bja bjc bjj bjk bka bkb bkc bkk bko boa bob boc boj bok boo c-- c-j caa cab cac caj cak cao cba cbb cbc cbj cbk cbo cca ccb ccc ccj cck cco cja cjb cjc cjk cka ckb ckc cko co- coa cob coc coj cok coo jaa jab jac jaj jak jao jba jbc jbj jbk jbo jca jcb jcc jck jco jja jjb jjc jjj jjk jka jkb jkk jko joa job joc joj jok joo ka- kaa kab kac kaj kak kao kba kbb kbc kbk kbo kca kcb kcc kck kjb kjc kkb kkc kkk koa kob koc kok koo oaa oab oac oaj oak oao ob- oba obb obc obj obk obo oc- oca ocb occ ocj ock oco oja ojb ojc ojo oka okb okc okj okk oko oo- ooa oob ooc ook ooo