a-a a-b a-i aaa aab aai aak aan aao aap aas ab- aba abb abi abk abn abo abp abs ai- aia aib aii aik ain aio aip ais aka akb aki akk akn ako akp aks an- ana anb ani ank ann ano anp ans aoa aob aoi aok aon aoo aop aos ap- apa apb api apk apn apo app aps as- asa asb asi ask asn aso asp ass b-p baa bab bai bak ban bao bap bas bba bbb bbi bbk bbn bbo bbp bbs bi- bia bib bii bik bin bio bip bis bka bkb bkk bkn bko bkp bks bna bnb bni bnk bnn bno bnp bns boa bob boi bok bon boo bop bos bpa bpb bpi bpn bpo bpp bps bsa bsb bsi bsk bsn bso bsp bss ia- iaa iab iai ian iao iap ias iba ibb ibi ibk ibn ibo ibp ibs iia iib iii iin iio iip iis ika ikb iki ikk iko iks in- ina inb ini ink inn ino inp ins io- ioa iob ioi ion ioo iop ios ipa ipb ipi ipn ipo ipp ips is- isa isb isi isk isn iso isp iss ka- kaa kab kai kak kan kao kap kas kba kbb kbi kbk kbn kbo kbp kbs kia kib kii kik kin kio kip kis kkb kki kkk kkn kkp kks kn- kna kni knk knn kno knp koa kob koi kok kon koo kop kos kpa kpi kpk kpn kpo kpp kps ksa ksb ksi ksk ksn kso ksp kss n-i naa nab nai nak nan nao nap nas nba nbb nbi nbk nbn nbo nbp nbs nia nib nii nik nin nio nip nis nka nki nkk nkn nko nkp nks nna nnb nni nnk nnn nno nnp nns no- noa nob noi nok non noo nop nos npa npb npi npn npo npp nps nsa nsb nsi nsk nsn nso nsp nss o-i oaa oab oai oak oan oao oap oas ob- oba obb obi obk obn obo obp obs oia oib oii oik oin oio oip ois oka okb oki okk oko okp oks on- ona onb oni onk onn ono onp ons oo- ooa oob ooi ook oon ooo oop oos op- opa opb opi opk opn opo opp ops os- osa osb osi osk osn oso osp oss p-p paa pab pai pak pan pao pap pas pba pbb pbi pbk pbn pbo pbp pbs pia pib pii pik pin pio pip pis pka pkb pki pkn pko pkp pks pn- pna pnb pni pnk pnn pno pnp pns poa pob poi pok pon poo pop pos ppa ppb ppi ppk ppn ppo ppp pps ps- psa psb psi psk psn pso psp pss saa sab sai sak san sao sap sas sba sbb sbi sbk sbn sbo sbp sbs sia sib sii sik sin sio sip sis sk- ska skb ski skk sko skp sks sna snb sni snk snn sno snp sns soa sob soi sok son soo sop sos spa spb spi spk spn spo spp sps ss- ssa ssb ssi ssk ssn sso ssp sss