a-a a-b a-c a-t aaa aab aac aan aao aas aat ab- aba abb abc abn abo abs abt ac- aca acb acc acn aco acs act an- ana anb anc ann ano ans ant aoa aob aoc aon aoo aos aot as- asa asb asc asn aso ass ast at- ata atb atc atn ato ats att baa bab bac ban bao bas bat bba bbb bbc bbn bbo bbs bbt bca bcb bcc bcn bco bcs bct bna bnb bnc bnn bno bns bnt boa bob boc bon boo bos bot bsa bsb bsc bsn bso bss bst bta btb btc btn bto bts btt c-- caa cab cac can cao cas cat cba cbb cbc cbn cbo cbs cbt cca ccb ccc ccn cco ccs cct cn- cna cnb cnc cnn cno cns cnt co- coa cob coc con coo cos cot csa csb csc csn cso css cst cta ctb ctc ctn cto cts ctt naa nab nac nan nao nas nat nba nbb nbc nbn nbo nbs nbt nca ncb ncc ncn nco ncs nct nna nnb nnc nnn nno nns nnt no- noa nob noc non noo nos not nsa nsb nsc nsn nso nss nst nta ntb ntc ntn nto nts ntt oaa oab oac oan oao oas oat ob- oba obb obc obn obo obs obt oc- oca ocb occ ocn oco ocs oct on- ona onb onc onn ono ons ont oo- ooa oob ooc oon ooo oos oot os- osa osb osc osn oso oss ost ot- ota otb otc otn oto ots ott saa sab sac san sao sas sat sba sbb sbc sbn sbo sbs sbt sca scb scc scn sco scs sct sna snb snc snn sno sns snt soa sob soc son soo sos sot ss- ssa ssb ssc ssn sso sss sst sta stb stc stn sto sts stt taa tab tac tan tao tas tat tba tbb tbc tbn tbo tbs tbt tca tcb tcc tcn tco tcs tct tna tnb tnc tnn tno tns tnt to- toa tob toc ton too tos tot tsa tsb tsc tsn tso tss tst tta ttb ttc ttn tto tts ttt