-er a-a a-b a-c aaa aab aac aae aag aar aau ab- aba abb abc abe abg abr abu ac- aca acb acc ace acg acr acu aea aeb aec aee aeg aer aeu ag- aga agb agc age agg agr agu ar- ara arb arc are arg arr aru au- aua aub auc aue aug aur b-u baa bab bac bae bag bar bau bba bbb bbc bbe bbg bbr bbu bca bcb bcc bce bcg bcr bcu be- bea beb bec bee beg ber beu bga bgb bgc bge bgg bgr bgu bra brb bre brg brr bru bua bub buc bue bug bur buu c-- caa cab cac cae cag car cau cba cbb cbc cbe cbg cbr cbu cca ccb ccc cce ccg ccr ccu ce- cea ceb cec cee ceg cer ceu cga cgb cgc cge cgg cgr cgu cra crb crc cre crg crr cru cua cub cuc cue cug cur cuu eaa eab eac eae eag ear eau eba ebb ebc ebe ebg ebr ebu ec- eca ecb ecc ece ecg ecr ecu eea eeb eec eee eeg eer ega egb egc ege egg egr egu era erb erc ere erg err eru eu- eua eub euc eue eug eur gaa gab gac gae gag gar gau gba gbc gbe gbg gbr gbu gca gcb gcc gce gcg gcr gcu ge- gea geb gec gee geg ger geu gga ggb ggc ggg ggr ggu gra grb grc gre grg grr gru gu- gua gub guc gue gug gur guu ra- raa rab rac rae rag rar rau rba rbb rbc rbe rbg rbr rbu rca rcb rcc rce rcg rcr rcu re- rea reb rec ree reg rer reu rga rgb rgc rge rgg rgr rra rrb rrc rrg rrr rru rua rub ruc rue rug rur ruu ua- uaa uab uac uae uag uar uau uba ubb ubc ube ubg ubr ubu uca ucb ucc uce ucg ucr ucu uea ueb uec uee ueg uer uga ugb ugc uge ugg ugr ugu ur- ura urb urc ure urg urr uru uua uuc uue uug uur uuu