a-a a-b a-i a-t aaa aab aai aar aas aat aau ab- aba abb abi abr abs abt abu ai- aia aib aii air ais ait aiu ar- ara arb ari arr ars art aru as- asa asb asi asr ass ast asu at- ata atb ati atr ats att atu au- aua aub aui aur aus aut b-u baa bab bai bar bas bat bau bba bbb bbi bbr bbs bbt bbu bi- bia bib bii bir bis bit biu bra brb bri brr brs brt bru bsa bsb bsi bsr bss bst bsu bta btb bti btr bts btt btu bua bub bui bur bus but buu ia- iaa iab iai iar ias iat iau iba ibb ibi ibr ibs ibt ibu iia iib iii iir iis iit iiu ir- ira irb iri irr irs irt iru is- isa isb isi isr iss ist isu ita itb iti its itt itu iu- iua iub iui iur ius iut ra- raa rab rai rar ras rat rau rba rbb rbi rbr rbs rbt rbu ria rib rii rir ris rit rra rrb rri rrr rrs rrt rru rsa rsb rsi rsr rss rst rsu rta rtb rti rtr rts rtt rtu rua rub rui rur rus rut ruu saa sab sai sar sas sat sau sba sbb sbi sbr sbs sbt sbu sia sib sii sir sis sit siu sr- sra srb sri srr srs srt ss- ssa ssb ssi ssr sss sst ssu sta stb sti str sts stt stu sua sub sui sur sus sut suu taa tab tai tar tas tat tau tba tbb tbi tbr tbs tbt tbu tia tib tii tir tis tit tiu tra trb tri trr trs trt tru tsa tsb tsi tsr tss tst tsu tta ttb tti ttr tts ttt ttu tua tub tui tur tus tut tuu ua- uaa uab uai uar uas uat uau uba ubb ubi ubr ubs ubt ubu uia uib uii uir uis uit uiu ur- ura urb uri urr urs urt uru usa usb usi usr uss ust usu uta utb uti utr uts utt utu uua uur uus uut uuu