a-a a-b a-c a-t aaa aab aac aap aar aat ab- aba abb abc abp abr abt ac- aca acb acc acp acr act ap- apa apb apc app apr apt ar- ara arb arc arp arr art at- ata atb atc atp atr att b-p baa bab bac bap bar bat bba bbb bbc bbp bbr bbt bca bcb bcc bcp bcr bct bpa bpb bpc bpp bpr bpt bra brb brp brr brt bta btb btc btp btr btt c-- caa cab cac cap car cat cba cbb cbc cbp cbr cbt cca ccb ccc ccp ccr cct cpa cpb cpc cpp cpr cpt cra crb crc crp crr crt cta ctb ctc ctp ctr ctt p-p paa pab pac pap par pat pba pbb pbc pbp pbr pbt pca pcb pcc pcp pcr pct ppa ppb ppc ppp ppr ppt pra prb prc prp prr prt pt- pta ptb ptc ptp ptr ptt ra- raa rab rac rap rar rat rba rbb rbc rbp rbr rbt rca rcb rcc rcp rcr rct rpa rpb rpc rpp rpr rpt rra rrb rrc rrp rrr rrt rta rtb rtc rtp rtr rtt taa tab tac tap tar tat tba tbb tbc tbp tbr tbt tca tcb tcc tcp tcr tct tpa tpb tpc tpp tpr tpt tra trb trc trp trr trt tta ttb ttc ttp ttr ttt