a-a a-b a-c aaa aab aac aan aao aas aau ab- aba abb abc abn abo abs abu ac- aca acb acc acn aco acs acu an- ana anb anc ann ano ans anu aoa aob aoc aon aoo aos aou as- asa asb asc asn aso ass asu au- aua aub auc aun auo aus b-u baa bab bac ban bao bas bau bba bbb bbc bbn bbo bbs bbu bca bcb bcc bcn bco bcs bcu bna bnb bnc bnn bno bns bnu boa bob boc bon boo bos bou bsa bsb bsc bsn bso bss bsu bua bub buc bun buo bus buu c-- caa cab cac can cao cas cau cba cbb cbc cbn cbo cbs cbu cca ccb ccc ccn cco ccs ccu cn- cna cnb cnc cnn cno cns cnu co- coa cob coc con coo cos cou csa csb csc csn cso css csu cua cub cuc cun cuo cus cuu naa nab nac nan nao nas nau nba nbb nbc nbn nbo nbs nbu nca ncb ncc ncn nco ncs ncu nna nnb nnc nnn nno nns nnu no- noa nob noc non noo nos nou nsa nsb nsc nsn nso nss nsu nua nub nuc nun nuo nus nuu oaa oab oac oan oao oas oau ob- oba obb obc obn obo obs obu oc- oca ocb occ ocn oco ocs ocu on- ona onb onc onn ono ons onu oo- ooa oob ooc oon ooo oos os- osa osb osc osn oso oss osu ou- oua ouc oun ouo ous saa sab sac san sao sas sau sba sbb sbc sbn sbo sbs sbu sca scb scc scn sco scs scu sna snb snc snn sno sns snu soa sob soc son soo sos sou ss- ssa ssb ssc ssn sso sss ssu sua sub suc sun suo sus suu ua- uaa uab uac uan uao uas uau uba ubb ubc ubn ubo ubs ubu uca ucb ucc ucn uco ucs ucu un- una unb unc unn uno uns unu uoa uob uoc uon uoo uos usa usb usc usn uso uss usu uua uuc uun uus uuu