a-a a-b a-c aaa aab aac aam aao aar ab- aba abb abc abm abo abr ac- aca acb acc acm aco acr ama amb amc amm amo amr aoa aob aoc aom aoo aor ar- ara arb arc arm aro arr baa bab bac bam bao bar bba bbb bbc bbm bbo bbr bca bcb bcc bcm bco bcr bma bmb bmc bmm bmo bmr boa bob boc bom boo bor bra brb brm bro brr c-- caa cab cac cam cao car cba cbb cbc cbm cbo cbr cca ccb ccc ccm cco ccr cma cmb cmc cmm cmo cmr co- coa cob coc com coo cor cra crb crc crm cro crr m-o m-r maa mab mac mam mao mar mba mbb mbc mbm mbo mbr mc- mca mcb mcc mcm mco mcr mma mmb mmc mmm mmo mmr moa mob moc mom moo mor mra mrb mrc mrm mro mrr oaa oab oac oam oao oar ob- oba obb obc obm obo obr oc- oca ocb occ ocm oco ocr om- oma omb omc omm omo omr oo- ooa oob ooc oom ooo oor or- ora orb orc orm oro orr ra- raa rab rac ram rao rar rba rbb rbc rbm rbo rbr rca rcb rcc rcm rco rcr rma rmb rmc rmm rmo rmr roa rob roc rom roo ror rra rrb rrc rrm rrr