a-a a-b a-c aaa aab aac aad aao aar aau ab- aba abb abc abd abo abr abu ac- aca acb acc acd aco acr acu ad- ada adb adc add ado adr adu aoa aob aoc aod aoo aor aou ar- ara arb arc ard aro arr aru au- aua aub auc aud auo aur b-u baa bab bac bad bao bar bau bba bbb bbc bbd bbo bbr bbu bca bcb bcc bcd bco bcr bcu bda bdb bdc bdd bdo bdr bdu boa bob boc bod boo bor bou bra brb brd bro brr bru bua bub buc bud buo bur buu c-- caa cab cac cad cao car cau cba cbb cbc cbd cbo cbr cbu cca ccb ccc ccd cco ccr ccu cda cdb cdc cdd cdo cdr cdu co- coa cob coc cod coo cor cou cra crb crc crd cro crr cru cua cub cuc cud cuo cur cuu daa dab dac dad dao dar dau dba dbb dbc dbd dbo dbr dbu dca dcb dcc dcd dco dcr dcu dda ddb ddc ddd ddo ddr ddu doa dob doc dod doo dor dou dra drb drc drd dro drr dru dua dub duc dud duo dur oaa oab oac oad oao oar oau ob- oba obb obc obd obo obr obu oc- oca ocb occ ocd oco ocr ocu oda odb odc odd odo odr odu oo- ooa oob ooc ood ooo oor or- ora orb orc ord oro orr oru ou- oua ouc oud ouo our ra- raa rab rac rad rao rar rau rba rbb rbc rbd rbo rbr rbu rca rcb rcc rcd rco rcr rcu rda rdb rdc rdd rdo rdr rdu roa rob roc rod roo ror rou rra rrb rrc rrd rrr rru rua rub ruc rud ruo rur ruu ua- uaa uab uac uad uao uar uau uba ubb ubc ubo ubr ubu uca ucb ucc ucd uco ucr ucu uda udb udc udd udo udr udu uoa uob uoc uod uoo uor ur- ura urb urc urd uro urr uru uua uuc uur uuu