a-a a-b a-c aaa aab aac aao aar aau aay ab- aba abb abc abo abr abu aby ac- aca acb acc aco acr acu acy aoa aob aoc aoo aor aou ar- ara arb arc aro arr aru ary au- aua aub auc auo aur ay- aya ayc ayo ayr ayu b-u baa bab bac bao bar bau bay bba bbb bbc bbo bbr bbu bby bca bcb bcc bco bcr bcu bcy boa bob boc boo bor bou boy bra brb bro brr bru bry bua bub buc buo bur buu buy by- bya byc byo byr byu c-- caa cab cac cao car cau cay cba cbb cbc cbo cbr cbu cby cca ccb ccc cco ccr ccu co- coa cob coc coo cor cou coy cra crb crc cro crr cru cry cua cub cuc cuo cur cuu cuy cya cyb cyc cyo cyr oaa oab oac oao oar oau ob- oba obb obc obo obr obu oby oc- oca ocb occ oco ocr ocu oo- ooa oob ooc ooo oor or- ora orb orc oro orr oru ory ou- oua ouc ouo our oya oyo ra- raa rab rac rao rar rau ray rba rbb rbc rbo rbr rbu rca rcb rcc rco rcr rcu roa rob roc roo ror rou roy rra rrb rrc rrr rru rua rub ruc ruo rur ruu ruy ry- rya ryc ryo ryr ryu ryy ua- uaa uab uac uao uar uau uay uba ubb ubc ubo ubr ubu uby uca ucb ucc uco ucr ucu uoa uob uoc uoo uor ur- ura urb urc uro urr uru ury uua uuc uur uuu uyc uyo uyu yaa yab yac yao yar yau yay ybc ybr yby yca ycc yco ycu ycy yob yoc yoo yor you yoy yra yrc yro yru yua yuo yur yuu yuy yyb yyc yyu yyy