a-a a-b aaa aab aaf aak aaw ab- aba abb abf abk abw af- afa afb aff afk afw aka akb akk akw aw- awa awb awf awk aww baa bab baf bak baw bba bbb bbf bbk bbw bfa bfb bff bka bkb bkf bkk bkw bwa bwb bwf bwk faa fab faf fak faw fba fbb fbf fbk fbw ffa fff ffk ffw fka fkb fkf fkk fwa fwb fwf ka- kaa kab kaf kak kaw kba kbb kbf kbk kbw kfa kff kfw kkb kkk kw- kwa kwf kwk kww waa wab waf wak waw wba wbb wbf wbw wfa wfb wff wfk wfw wka wkb wkf wkw wwa wwf www