a-a a-b a-c aaa aab aac aar aas aau aay ab- aba abb abc abr abs abu aby ac- aca acb acc acr acs acu acy ar- ara arb arc arr ars aru ary as- asa asb asc asr ass asu asy au- aua aub auc aur aus ay- aya ayc ayr ays ayu b-u baa bab bac bar bas bau bay bba bbb bbc bbr bbs bbu bby bca bcb bcc bcr bcs bcu bcy bra brb brr brs bru bry bsa bsb bsc bsr bss bsu bsy bua bub buc bur bus buu buy by- bya byc byr bys byu c-- caa cab cac car cas cau cay cba cbb cbc cbr cbs cbu cby cca ccb ccc ccr ccs ccu cra crb crc crr crs cru cry csa csb csc csr css csu csy cua cub cuc cur cus cuu cuy cya cyb cyc cyr cys ra- raa rab rac rar ras rau ray rba rbb rbc rbr rbs rbu rca rcb rcc rcr rcs rcu rra rrb rrc rrr rrs rru rsa rsb rsc rsr rss rsu rua rub ruc rur rus ruu ruy ry- rya ryc ryr rys ryu ryy saa sab sac sar sas sau say sba sbb sbc sbr sbs sbu sby sca scb scc scr scs scu sr- sra srb src srr srs sry ss- ssa ssb ssc ssr sss ssu sua sub suc sur sus suu suy sy- sya syb syc syr sys syu ua- uaa uab uac uar uas uau uay uba ubb ubc ubr ubs ubu uby uca ucb ucc ucr ucs ucu ur- ura urb urc urr urs uru ury usa usb usc usr uss usu uua uuc uur uus uuu uyc uys uyu yaa yab yac yar yas yau yay ybc ybr ybs yby yca ycc ycs ycu ycy yra yrc yrs yru ysa ysb ysc ysr yss ysu ysy yua yur yus yuu yuy yyb yyc yys yyu yyy