a-a a-b aaa aab aah aan aao aar ab- aba abb abh abn abo abr aha ahb ahh ahn aho ahr an- ana anb anh ann ano anr aoa aob aoh aon aoo aor ar- ara arb arh arn aro arr baa bab bah ban bao bar bba bbb bbh bbn bbo bbr bha bhb bhh bho bhr bna bnb bnn bno bnr boa bob boh bon boo bor bra brb brh brn bro brr haa hab hah han hao har hba hbb hbh hbn hbo hbr hha hhb hhh hhn hho hhr hna hnb hnh hnn hno hoa hob hoh hon hoo hor hr- hra hrb hrh hrn hro hrr naa nab nah nan nao nar nba nbb nbn nbo nbr nha nhb nhh nhn nhr nna nnb nnh nnn nno no- noa nob noh non noo nor nra nrb nrn nro nrr oaa oab oah oan oao oar ob- oba obb obh obn obo obr oha ohh ohn oho ohr on- ona onb onh onn ono onr oo- ooa oob ooh oon ooo oor or- ora orb orh orn oro orr ra- raa rab rah ran rao rar rba rbb rbh rbn rbo rbr rh- rha rhb rhh rhn rho rhr rna rnb rnh rnn rno rnr roa rob roh ron roo ror rra rrb rrh rrn rrr