a-a a-b a-c a-t aaa aab aac aao aap aat ab- aba abb abc abo abp abt ac- aca acb acc aco acp act aoa aob aoc aoo aop aot ap- apa apb apc apo app apt at- ata atb atc ato atp att b-p baa bab bac bao bap bat bba bbb bbc bbo bbp bbt bca bcb bcc bco bcp bct boa bob boc boo bop bot bpa bpb bpc bpo bpp bpt bta btb btc bto btp btt c-- caa cab cac cao cap cat cba cbb cbc cbo cbp cbt cca ccb ccc cco ccp cct co- coa cob coc coo cop cot cpa cpb cpc cpo cpp cpt cta ctb ctc cto ctp ctt oaa oab oac oao oap oat ob- oba obb obc obo obp obt oc- oca ocb occ oco ocp oct oo- ooa oob ooc ooo oop oot op- opa opb opc opo opp opt ot- ota otb otc oto otp ott p-p paa pab pac pao pap pat pba pbb pbc pbo pbp pbt pca pcb pcc pco pcp pct poa pob poc poo pop pot ppa ppb ppc ppo ppp ppt pt- pta ptb ptc pto ptp ptt taa tab tac tao tap tat tba tbb tbc tbo tbp tbt tca tcb tcc tco tcp tct to- toa tob toc too top tot tpa tpb tpc tpo tpp tpt tta ttb ttc tto ttp ttt