a-a a-b a-c aaa aab aac aad aak aao aap aar ab- aba abb abc abd abk abo abp abr ac- aca acb acc acd ack aco acp acr ad- ada adb adc add adk ado adp adr aka akb akc akd akk ako akp akr aoa aob aoc aod aok aoo aop aor ap- apa apb apc apd apk apo app apr ar- ara arb arc ard ark aro arp arr b-p baa bab bac bad bak bao bap bar bba bbb bbc bbd bbk bbo bbp bbr bca bcb bcc bcd bck bco bcp bcr bda bdb bdc bdd bdk bdo bdp bdr bka bkb bkc bkk bko bkp bkr boa bob boc bod bok boo bop bor bpa bpb bpc bpd bpo bpp bpr bra brb brd brk bro brp brr c-- caa cab cac cad cak cao cap car cba cbb cbc cbd cbk cbo cbp cbr cca ccb ccc ccd cck cco ccp ccr cda cdb cdc cdd cdk cdo cdp cdr cka ckb ckc ckd cko co- coa cob coc cod cok coo cop cor cpa cpb cpc cpd cpk cpo cpp cpr cra crb crc crd crk cro crp crr daa dab dac dad dak dao dap dar dba dbb dbc dbd dbk dbo dbp dbr dca dcb dcc dcd dck dco dcp dcr dda ddb ddc ddd ddk ddo ddp ddr dka dkb dkc dkk dko dkp dkr doa dob doc dod dok doo dop dor dpa dpb dpc dpd dpk dpo dpp dpr dra drb drc drd drk dro drp drr ka- kaa kab kac kad kak kao kap kar kba kbb kbc kbd kbk kbo kbp kbr kca kcb kcc kcd kck kcp kcr kda kdb kdc kdk kdo kdp kdr kkb kkc kkk kkp kkr koa kob koc kod kok koo kop kor kpa kpc kpd kpk kpo kpp kpr kra krc krd krk kro krp krr oaa oab oac oad oak oao oap oar ob- oba obb obc obd obk obo obp obr oc- oca ocb occ ocd ock oco ocp ocr oda odb odc odd odo odp odr oka okb okc okd okk oko okp okr oo- ooa oob ooc ood ook ooo oop oor op- opa opb opc opd opk opo opp opr or- ora orb orc ord ork oro orp orr p-p paa pab pac pad pak pao pap par pba pbb pbc pbd pbk pbo pbp pbr pca pcb pcc pcd pck pco pcp pcr pda pdb pdc pdd pdk pdo pdp pdr pka pkb pkc pkd pko pkp pkr poa pob poc pod pok poo pop por ppa ppb ppc ppd ppk ppo ppp ppr pra prb prc prd prk pro prp prr ra- raa rab rac rad rak rao rap rar rba rbb rbc rbd rbk rbo rbp rbr rca rcb rcc rcd rco rcp rcr rda rdb rdc rdd rdo rdp rdr rkb rkc rkk rko rkp roa rob roc rod rok roo rop ror rpa rpb rpc rpd rpk rpo rpp rpr rra rrb rrc rrd rrk rrp rrr