a-a a-b a-c aaa aab aac aan aas aau ab- aba abb abc abn abs abu ac- aca acb acc acn acs acu an- ana anb anc ann ans anu as- asa asb asc asn ass asu au- aua aub auc aun aus b-u baa bab bac ban bas bau bba bbb bbc bbn bbs bbu bca bcb bcc bcn bcs bcu bna bnb bnc bnn bns bnu bsa bsb bsc bsn bss bsu bua bub buc bun bus buu c-- caa cab cac can cas cau cba cbb cbc cbn cbs cbu cca ccb ccc ccn ccs ccu cn- cna cnb cnc cnn cns cnu csa csb csc csn css csu cua cub cuc cun cus cuu naa nab nac nan nas nau nba nbb nbc nbn nbs nbu nca ncb ncc ncn ncs ncu nna nnb nnc nnn nns nnu nsa nsb nsc nsn nss nsu nua nub nuc nun nus nuu saa sab sac san sas sau sba sbb sbc sbn sbs sbu sca scb scc scn scs scu sna snb snc snn sns snu ss- ssa ssb ssc ssn sss ssu sua sub suc sun sus suu ua- uaa uab uac uan uas uau uba ubb ubc ubn ubs ubu uca ucb ucc ucn ucs ucu un- una unb unc unn uns unu usa usb usc usn uss usu uua uuc uun uus uuu