a-a a-b a-c aaa aab aac aad aao aap aar ab- aba abb abc abd abo abp abr ac- aca acb acc acd aco acp acr ad- ada adb adc add ado adp adr aoa aob aoc aod aoo aop aor ap- apa apb apc apd apo app apr ar- ara arb arc ard aro arp arr b-p baa bab bac bad bao bap bar bba bbb bbc bbd bbo bbp bbr bca bcb bcc bcd bco bcp bcr bda bdb bdc bdd bdo bdp bdr boa bob boc bod boo bop bor bpa bpb bpc bpd bpo bpp bpr bra brb brd bro brp brr c-- caa cab cac cad cao cap car cba cbb cbc cbd cbo cbp cbr cca ccb ccc ccd cco ccp ccr cda cdb cdc cdd cdo cdp cdr co- coa cob coc cod coo cop cor cpa cpb cpc cpd cpo cpp cpr cra crb crc crd cro crp crr daa dab dac dad dao dap dar dba dbb dbc dbd dbo dbp dbr dca dcb dcc dcd dco dcp dcr dda ddb ddc ddd ddo ddp ddr doa dob doc dod doo dop dor dpa dpb dpc dpd dpo dpp dpr dra drb drc drd dro drp drr oaa oab oac oad oao oap oar ob- oba obb obc obd obo obp obr oc- oca ocb occ ocd oco ocp ocr oda odb odc odd odo odp odr oo- ooa oob ooc ood ooo oop oor op- opa opb opc opd opo opp opr or- ora orb orc ord oro orp orr p-p paa pab pac pad pao pap par pba pbb pbc pbd pbo pbp pbr pca pcb pcc pcd pco pcp pcr pda pdb pdc pdd pdo pdp pdr poa pob poc pod poo pop por ppa ppb ppc ppd ppo ppp ppr pra prb prc prd pro prp prr ra- raa rab rac rad rao rap rar rba rbb rbc rbd rbo rbp rbr rca rcb rcc rcd rco rcp rcr rda rdb rdc rdd rdo rdp rdr roa rob roc rod roo rop ror rpa rpb rpc rpd rpo rpp rpr rra rrb rrc rrd rrp rrr