a-a a-b a-c aaa aab aac aao aas aav ab- aba abb abc abo abs abv ac- aca acb acc aco acs acv aoa aob aoc aoo aos aov as- asa asb asc aso ass asv av- ava avb avc avo avs baa bab bac bao bas bav bba bbb bbc bbo bbs bca bcb bcc bco bcs bcv boa bob boc boo bos bov bsa bsb bsc bso bss bsv bva bvb bvc bvo bvs bvv c-- caa cab cac cao cas cav cba cbb cbc cbo cbs cbv cca ccb ccc cco ccs ccv co- coa cob coc coo cos cov csa csb csc cso css csv cva cvb cvc cvo cvs cvv oaa oab oac oao oas oav ob- oba obb obc obo obs obv oc- oca ocb occ oco ocs ocv oo- ooa oob ooc ooo oos oov os- osa osb osc oso oss osv ov- ova ovb ovc ovo ovs ovv saa sab sac sao sas sav sba sbb sbc sbo sbs sbv sca scb scc sco scs scv soa sob soc soo sos sov ss- ssa ssb ssc sso sss ssv sva svb svc svo svs svv v-a vaa vab vac vao vas vav vba vbc vbo vbs vbv vca vcc vco vcs voa vob voc voo vos vov vsa vsb vsc vso vss vsv vva vvb vvc vvo vvs vvv