a-a a-b a-c aaa aab aac aah aan aao aar ab- aba abb abc abh abn abo abr ac- aca acb acc ach acn aco acr aha ahb ahc ahh ahn aho ahr an- ana anb anc anh ann ano anr aoa aob aoc aoh aon aoo aor ar- ara arb arc arh arn aro arr baa bab bac bah ban bao bar bba bbb bbc bbh bbn bbo bbr bca bcb bcc bch bcn bco bcr bha bhb bhc bhh bho bhr bna bnb bnc bnn bno bnr boa bob boc boh bon boo bor bra brb brh brn bro brr c-- caa cab cac cah can cao car cba cbb cbc cbh cbn cbo cbr cca ccb ccc cch ccn cco ccr ch- cha chb chc chh chn cho chr cn- cna cnb cnc cnh cnn cno cnr co- coa cob coc coh con coo cor cra crb crc crh crn cro crr haa hab hac hah han hao har hba hbb hbc hbh hbn hbo hbr hca hcb hcc hch hcn hco hcr hha hhb hhc hhh hhn hho hhr hna hnb hnc hnh hnn hno hoa hob hoc hoh hon hoo hor hr- hra hrb hrc hrh hrn hro hrr naa nab nac nah nan nao nar nba nbb nbc nbn nbo nbr nca ncb ncc nch ncn nco ncr nha nhb nhc nhh nhn nhr nna nnb nnc nnh nnn nno no- noa nob noc noh non noo nor nra nrb nrc nrn nro nrr oaa oab oac oah oan oao oar ob- oba obb obc obh obn obo obr oc- oca ocb occ och ocn oco ocr oha ohc ohh ohn oho ohr on- ona onb onc onh onn ono onr oo- ooa oob ooc ooh oon ooo oor or- ora orb orc orh orn oro orr ra- raa rab rac rah ran rao rar rba rbb rbc rbh rbn rbo rbr rca rcb rcc rch rcn rco rcr rh- rha rhb rhc rhh rhn rho rhr rna rnb rnc rnh rnn rno rnr roa rob roc roh ron roo ror rra rrb rrc rrh rrn rrr