a-a a-b a-c aaa aab aac aar aav ab- aba abb abc abr abv ac- aca acb acc acr acv ar- ara arb arc arr arv av- ava avb avc avr baa bab bac bar bav bba bbb bbc bbr bca bcb bcc bcr bcv bra brb brr brv bva bvb bvc bvr bvv c-- caa cab cac car cav cba cbb cbc cbr cbv cca ccb ccc ccr ccv cra crb crc crr crv cva cvb cvc cvr cvv ra- raa rab rac rar rav rba rbb rbc rbr rca rcb rcc rcr rcv rra rrb rrc rrr rva rvb rvc rvr rvv v-a vaa vab vac var vav vba vbc vbr vbv vca vcc vcr vra vrb vrc vrr vva vvb vvc vvr vvv