a-a a-b a-c aaa aab aac aad aan aao aap aar ab- aba abb abc abd abn abo abp abr ac- aca acb acc acd acn aco acp acr ad- ada adb adc add adn ado adp adr an- ana anb anc and ann ano anp anr aoa aob aoc aod aon aoo aop aor ap- apa apb apc apd apn apo app apr ar- ara arb arc ard arn aro arp arr b-p baa bab bac bad ban bao bap bar bba bbb bbc bbd bbn bbo bbp bbr bca bcb bcc bcd bcn bco bcp bcr bda bdb bdc bdd bdo bdp bdr bna bnb bnc bnd bnn bno bnp bnr boa bob boc bod bon boo bop bor bpa bpb bpc bpd bpn bpo bpp bpr bra brb brd brn bro brp brr c-- caa cab cac cad can cao cap car cba cbb cbc cbd cbn cbo cbp cbr cca ccb ccc ccd ccn cco ccp ccr cda cdb cdc cdd cdn cdo cdp cdr cn- cna cnb cnc cnd cnn cno cnp cnr co- coa cob coc cod con coo cop cor cpa cpb cpc cpd cpn cpo cpp cpr cra crb crc crd crn cro crp crr daa dab dac dad dan dao dap dar dba dbb dbc dbd dbn dbo dbp dbr dca dcb dcc dcd dcn dco dcp dcr dda ddb ddc ddd ddn ddo ddp ddr dna dnb dnc dnd dnn dno dnp dnr doa dob doc dod don doo dop dor dpa dpb dpc dpd dpn dpo dpp dpr dra drb drc drd drn dro drp drr naa nab nac nad nan nao nap nar nba nbb nbc nbd nbn nbo nbp nbr nca ncb ncc ncd ncn nco ncp ncr nda ndb ndc ndd ndn ndo ndp ndr nna nnb nnc nnn nno nnp no- noa nob noc nod non noo nop nor npa npb npc npd npn npo npp npr nra nrb nrc nrd nrn nro nrp nrr oaa oab oac oad oan oao oap oar ob- oba obb obc obd obn obo obp obr oc- oca ocb occ ocd ocn oco ocp ocr oda odb odc odd odn odo odp odr on- ona onb onc ond onn ono onp onr oo- ooa oob ooc ood oon ooo oop oor op- opa opb opc opd opn opo opp opr or- ora orb orc ord orn oro orp orr p-p paa pab pac pad pan pao pap par pba pbb pbc pbd pbn pbo pbp pbr pca pcb pcc pcd pcn pco pcp pcr pda pdb pdc pdd pdn pdo pdp pdr pn- pna pnb pnc pnd pnn pno pnp pnr poa pob poc pod pon poo pop por ppa ppb ppc ppd ppn ppo ppp ppr pra prb prc prd prn pro prp prr ra- raa rab rac rad ran rao rap rar rba rbb rbc rbd rbn rbo rbp rbr rca rcb rcc rcd rcn rco rcp rcr rda rdb rdc rdd rdn rdo rdp rdr rna rnb rnc rnd rnn rno rnp rnr roa rob roc rod ron roo rop ror rpa rpb rpc rpd rpn rpo rpp rpr rra rrb rrc rrd rrn rrp rrr