a-a a-b a-i aaa aab aai aan aao aap aar ab- aba abb abi abn abo abp abr ai- aia aib aii ain aio aip air an- ana anb ani ann ano anp anr aoa aob aoi aon aoo aop aor ap- apa apb api apn apo app apr ar- ara arb ari arn aro arp arr b-p baa bab bai ban bao bap bar bba bbb bbi bbn bbo bbp bbr bi- bia bib bii bin bio bip bir bna bnb bni bnn bno bnp bnr boa bob boi bon boo bop bor bpa bpb bpi bpn bpo bpp bpr bra brb bri brn bro brp brr ia- iaa iab iai ian iao iap iar iba ibb ibi ibn ibo ibp ibr iia iib iii iin iio iip iir in- ina inb ini inn ino inp inr io- ioa iob ioi ion ioo iop ior ipa ipb ipi ipn ipo ipp ipr ir- ira irb iri irn iro irp irr n-i naa nab nai nan nao nap nar nba nbb nbi nbn nbo nbp nbr nia nib nii nin nio nip nir nna nnb nni nnn nno nnp no- noa nob noi non noo nop nor npa npb npi npn npo npp npr nra nrb nri nrn nro nrp nrr o-i oaa oab oai oan oao oap oar ob- oba obb obi obn obo obp obr oia oib oii oin oio oip oir on- ona onb oni onn ono onp onr oo- ooa oob ooi oon ooo oop oor op- opa opb opi opn opo opp opr or- ora orb ori orn oro orp orr p-p paa pab pai pan pao pap par pba pbb pbi pbn pbo pbp pbr pia pib pii pin pio pip pir pn- pna pnb pni pnn pno pnp pnr poa pob poi pon poo pop por ppa ppb ppi ppn ppo ppp ppr pra prb pri prn pro prp prr ra- raa rab rai ran rao rap rar rba rbb rbi rbn rbo rbp rbr ria rib rii rin rio rip rir rna rnb rni rnn rno rnp rnr roa rob roi ron roo rop ror rpa rpb rpi rpn rpo rpp rpr rra rrb rri rrn rrp rrr