-er a-a a-b a-c aaa aab aac aae aag aao aar aau ab- aba abb abc abe abg abo abr abu ac- aca acb acc ace acg aco acr acu aea aeb aec aee aeg aeo aer aeu ag- aga agb agc age agg ago agr agu aoa aob aoc aoe aog aoo aor aou ar- ara arb arc are arg aro arr aru au- aua aub auc aue aug auo aur b-u baa bab bac bae bag bao bar bau bba bbb bbc bbe bbg bbo bbr bbu bca bcb bcc bce bcg bco bcr bcu be- bea beb bec bee beg beo ber beu bga bgb bgc bge bgg bgo bgr bgu boa bob boc boe bog boo bor bou bra brb bre brg bro brr bru bua bub buc bue bug buo bur buu c-- caa cab cac cae cag cao car cau cba cbb cbc cbe cbg cbo cbr cbu cca ccb ccc cce ccg cco ccr ccu ce- cea ceb cec cee ceg ceo cer ceu cga cgb cgc cge cgg cgo cgr cgu co- coa cob coc coe cog coo cor cou cra crb crc cre crg cro crr cru cua cub cuc cue cug cuo cur cuu eaa eab eac eae eag eao ear eau eba ebb ebc ebe ebg ebo ebr ebu ec- eca ecb ecc ece ecg eco ecr ecu eea eeb eec eee eeg eeo eer ega egb egc ege egg ego egr egu eo- eoa eob eoc eoe eog eoo eor eou era erb erc ere erg ero err eru eu- eua eub euc eue eug eur gaa gab gac gae gag gao gar gau gba gbc gbe gbg gbo gbr gbu gca gcb gcc gce gcg gco gcr gcu ge- gea geb gec gee geg geo ger geu gga ggb ggc ggg ggo ggr ggu goa gob goc goe gog goo gor gou gra grb grc gre grg gro grr gru gu- gua gub guc gue gug guo gur guu oaa oab oac oae oag oao oar oau ob- oba obb obc obe obg obo obr obu oc- oca ocb occ ocg oco ocr ocu oea oeb oec oee oeg oeo oer oga ogc oge ogg ogo oo- ooa oob ooc oog ooo oor or- ora orb orc ore org oro orr oru ou- oua ouc oue ouo our ra- raa rab rac rae rag rao rar rau rba rbb rbc rbe rbg rbo rbr rbu rca rcb rcc rce rcg rco rcr rcu re- rea reb rec ree reg reo rer reu rga rgb rgc rge rgg rgo rgr roa rob roc roe rog roo ror rou rra rrb rrc rrg rrr rru rua rub ruc rue rug ruo rur ruu ua- uaa uab uac uae uag uao uar uau uba ubb ubc ube ubg ubo ubr ubu uca ucb ucc uce ucg uco ucr ucu uea ueb uec uee ueg uer uga ugb ugc uge ugg ugo ugr ugu uoa uob uoc uoe uog uoo uor ur- ura urb urc ure urg uro urr uru uua uuc uue uug uur uuu