a-a a-b a-i aaa aab aai aan aao aap ab- aba abb abi abn abo abp ai- aia aib aii ain aio aip an- ana anb ani ann ano anp aoa aob aoi aon aoo aop ap- apa apb api apn apo app b-p baa bab bai ban bao bap bba bbb bbi bbn bbo bbp bi- bia bib bii bin bio bip bna bnb bni bnn bno bnp boa bob boi bon boo bop bpa bpb bpi bpn bpo bpp ia- iaa iab iai ian iao iap iba ibb ibi ibn ibo ibp iia iib iii iin iio iip in- ina inb ini inn ino inp io- ioa iob ioi ion ioo iop ipa ipb ipi ipn ipo ipp n-i naa nab nai nan nao nap nba nbb nbi nbn nbo nbp nia nib nii nin nio nip nna nnb nni nnn nno nnp no- noa nob noi non noo nop npa npb npi npn npo npp o-i oaa oab oai oan oao oap ob- oba obb obi obn obo obp oia oib oii oin oio oip on- ona onb oni onn ono onp oo- ooa oob ooi oon ooo oop op- opa opb opi opn opo opp p-p paa pab pai pan pao pap pba pbb pbi pbn pbo pbp pia pib pii pin pio pip pn- pna pnb pni pnn pno pnp poa pob poi pon poo pop ppa ppb ppi ppn ppo ppp