a-a a-b a-c a-t aaa aab aac aao aat aax ab- aba abb abc abo abt abx ac- aca acb acc aco act acx aoa aob aoc aoo aot aox at- ata atb atc ato att atx ax- axa axo axt axx baa bab bac bao bat bax bba bbb bbc bbo bbt bbx bca bcb bcc bco bct bcx boa bob boc boo bot box bta btb btc bto btt btx bxb bxo bxx c-- caa cab cac cao cat cax cba cbb cbc cbo cbt cbx cca ccb ccc cco cct ccx co- coa cob coc coo cot cox cta ctb ctc cto ctt ctx cxc cxo cxt cxx oaa oab oac oao oat oax ob- oba obb obc obo obt obx oc- oca ocb occ oco oct ocx oo- ooa oob ooc ooo oot oox ot- ota otb otc oto ott ox- oxa oxb oxc oxo oxt oxx t-x taa tab tac tao tat tax tba tbb tbc tbo tbt tca tcb tcc tco tct tcx to- toa tob toc too tot tox tta ttb ttc tto ttt ttx txt xaa xac xat xbc xbx xcb xcx xoa xoc xoo xot xox xtc xtx xxo xxx