a-a a-b aaa aab aao aar aaw aax ab- aba abb abo abr abw abx aoa aob aoo aor aow aox ar- ara arb aro arr arw arx aw- awa awb awo awr aww ax- axa axo axr axx baa bab bao bar baw bax bba bbb bbo bbr bbw bbx boa bob boo bor bow box bra brb bro brr brw brx bwa bwb bwo bwr bxb bxo bxw bxx oaa oab oao oar oaw oax ob- oba obb obo obr obw obx oo- ooa oob ooo oor oow oox or- ora orb oro orr orx owa owb owo oww ox- oxa oxb oxo oxx ra- raa rab rao rar raw rax rba rbb rbo rbr rbw rbx roa rob roo ror row rox rra rrb rrr rwa rwb rwr rxr waa wab wao war waw wax wba wbb wbo wbr wbw wbx woa wob woo wor wow wox wr- wra wro wrr wrw wrx wwa wwo www wxw xaa xar xbr xbx xoa xoo xor xox xrx xwa xxo xxx