a-a a-b a-c a-t aaa aab aac aao aap aas aat ab- aba abb abc abo abp abs abt ac- aca acb acc aco acp acs act aoa aob aoc aoo aop aos aot ap- apa apb apc apo app aps apt as- asa asb asc aso asp ass ast at- ata atb atc ato atp ats att b-p baa bab bac bao bap bas bat bba bbb bbc bbo bbp bbs bbt bca bcb bcc bco bcp bcs bct boa bob boc boo bop bos bot bpa bpb bpc bpo bpp bps bpt bsa bsb bsc bso bsp bss bst bta btb btc bto btp bts btt c-- caa cab cac cao cap cas cat cba cbb cbc cbo cbp cbs cbt cca ccb ccc cco ccp ccs cct co- coa cob coc coo cop cos cot cpa cpb cpc cpo cpp cps cpt csa csb csc cso csp css cst cta ctb ctc cto ctp cts ctt oaa oab oac oao oap oas oat ob- oba obb obc obo obp obs obt oc- oca ocb occ oco ocp ocs oct oo- ooa oob ooc ooo oop oos oot op- opa opb opc opo opp ops opt os- osa osb osc oso osp oss ost ot- ota otb otc oto otp ots ott p-p paa pab pac pao pap pas pat pba pbb pbc pbo pbp pbs pbt pca pcb pcc pco pcp pcs pct poa pob poc poo pop pos pot ppa ppb ppc ppo ppp pps ppt ps- psa psb psc pso psp pss pst pt- pta ptb ptc pto ptp pts ptt saa sab sac sao sap sas sat sba sbb sbc sbo sbp sbs sbt sca scb scc sco scp scs sct soa sob soc soo sop sos sot spa spb spc spo spp sps spt ss- ssa ssb ssc sso ssp sss sst sta stb stc sto stp sts stt taa tab tac tao tap tas tat tba tbb tbc tbo tbp tbs tbt tca tcb tcc tco tcp tcs tct to- toa tob toc too top tos tot tpa tpb tpc tpo tpp tps tpt tsa tsb tsc tso tsp tss tst tta ttb ttc tto ttp tts ttt