a-a a-b a-i aaa aab aai aar aav ab- aba abb abi abr abv ai- aia aib aii air aiv ar- ara arb ari arr arv av- ava avb avi avr baa bab bai bar bav bba bbb bbi bbr bi- bia bib bii bir biv bra brb bri brr brv bva bvb bvi bvr bvv i-v ia- iaa iab iai iar iav iba ibb ibi ibr ibv iia iib iii iir ir- ira irb iri irr irv iva ivb ivi ivr ivv ra- raa rab rai rar rav rba rbb rbi rbr ria rib rii rir riv rra rrb rri rrr rva rvb rvi rvr rvv v-a vaa vab vai var vav vba vbi vbr vbv vi- via vib vii vir viv vra vrb vri vrr vva vvb vvi vvr vvv