a-a a-b a-c a-t aaa aab aac aan aas aat aau ab- aba abb abc abn abs abt abu ac- aca acb acc acn acs act acu an- ana anb anc ann ans ant anu as- asa asb asc asn ass ast asu at- ata atb atc atn ats att atu au- aua aub auc aun aus aut b-u baa bab bac ban bas bat bau bba bbb bbc bbn bbs bbt bbu bca bcb bcc bcn bcs bct bcu bna bnb bnc bnn bns bnt bnu bsa bsb bsc bsn bss bst bsu bta btb btc btn bts btt btu bua bub buc bun bus but buu c-- caa cab cac can cas cat cau cba cbb cbc cbn cbs cbt cbu cca ccb ccc ccn ccs cct ccu cn- cna cnb cnc cnn cns cnt cnu csa csb csc csn css cst csu cta ctb ctc ctn cts ctt ctu cua cub cuc cun cus cut cuu naa nab nac nan nas nat nau nba nbb nbc nbn nbs nbt nbu nca ncb ncc ncn ncs nct ncu nna nnb nnc nnn nns nnt nnu nsa nsb nsc nsn nss nst nsu nta ntb ntc ntn nts ntt ntu nua nub nuc nun nus nut nuu saa sab sac san sas sat sau sba sbb sbc sbn sbs sbt sbu sca scb scc scn scs sct scu sna snb snc snn sns snt snu ss- ssa ssb ssc ssn sss sst ssu sta stb stc stn sts stt stu sua sub suc sun sus sut suu taa tab tac tan tas tat tau tba tbb tbc tbn tbs tbt tbu tca tcb tcc tcn tcs tct tcu tna tnb tnc tnn tns tnt tsa tsb tsc tsn tss tst tsu tta ttb ttc ttn tts ttt ttu tua tub tuc tun tus tut tuu ua- uaa uab uac uan uas uat uau uba ubb ubc ubn ubs ubt ubu uca ucb ucc ucn ucs uct ucu un- una unb unc unn uns unt unu usa usb usc usn uss ust usu uta utb utc utn uts utt utu uua uuc uun uus uut uuu