a-a a-b a-c a-t aaa aab aac aas aat aau ab- aba abb abc abs abt abu ac- aca acb acc acs act acu as- asa asb asc ass ast asu at- ata atb atc ats att atu au- aua aub auc aus aut b-u baa bab bac bas bat bau bba bbb bbc bbs bbt bbu bca bcb bcc bcs bct bcu bsa bsb bsc bss bst bsu bta btb btc bts btt btu bua bub buc bus but buu c-- caa cab cac cas cat cau cba cbb cbc cbs cbt cbu cca ccb ccc ccs cct ccu csa csb csc css cst csu cta ctb ctc cts ctt ctu cua cub cuc cus cut cuu saa sab sac sas sat sau sba sbb sbc sbs sbt sbu sca scb scc scs sct scu ss- ssa ssb ssc sss sst ssu sta stb stc sts stt stu sua sub suc sus sut suu taa tab tac tas tat tau tba tbb tbc tbs tbt tbu tca tcb tcc tcs tct tcu tsa tsb tsc tss tst tsu tta ttb ttc tts ttt ttu tua tub tuc tus tut tuu ua- uaa uab uac uas uat uau uba ubb ubc ubs ubt ubu uca ucb ucc ucs uct ucu usa usb usc uss ust usu uta utb utc uts utt utu uua uuc uus uut uuu