a-a a-b a-c aaa aab aac aao aaw ab- aba abb abc abo abw ac- aca acb acc aco acw aoa aob aoc aoo aow aw- awa awb awc awo aww baa bab bac bao baw bba bbb bbc bbo bbw bca bcb bcc bco boa bob boc boo bow bwa bwb bwc bwo c-- caa cab cac cao caw cba cbb cbc cbo cbw cca ccb ccc cco ccw co- coa cob coc coo cow cw- cwa cwb cwc cwo oaa oab oac oao oaw ob- oba obb obc obo obw oc- oca ocb occ oco ocw oo- ooa oob ooc ooo oow owa owb owc owo oww waa wab wac wao waw wba wbb wbc wbo wbw wca wcb wcc wco wcw woa wob woc woo wow wwa wwc wwo www