a-a a-b a-i aaa aab aai aao aap aax ab- aba abb abi abo abp abx ai- aia aib aii aio aip aix aoa aob aoi aoo aop aox ap- apa apb api apo app apx ax- axa axi axo axp axx b-p baa bab bai bao bap bax bba bbb bbi bbo bbp bbx bi- bia bib bii bio bip bix boa bob boi boo bop box bpa bpb bpi bpo bpp bpx bxb bxi bxo bxx ia- iaa iab iai iao iap iba ibb ibi ibo ibp ibx iia iib iii iio iip iix io- ioa iob ioi ioo iop ipa ipb ipi ipo ipp ipx ixi o-i oaa oab oai oao oap oax ob- oba obb obi obo obp obx oia oib oii oio oip oo- ooa oob ooi ooo oop oox op- opa opb opi opo opp opx ox- oxa oxb oxi oxo oxx p-p paa pab pai pao pap pax pba pbb pbi pbo pbp pbx pia pib pii pio pip pix poa pob poi poo pop pox ppa ppb ppi ppo ppp ppx xaa xap xbx xia xii xio xix xoa xoi xoo xop xox xpa xpb xpo xpp xxi xxo xxp xxx