a-a a-b aaa aab aae aag aak aas ab- aba abb abe abg abk abs aea aeb aee aeg aek aes ag- aga agb age agg agk ags aka akb ake akg akk aks as- asa asb ase asg ask ass baa bab bae bag bak bas bba bbb bbe bbg bbk bbs be- bea beb bee beg bek bes bga bgb bge bgg bgk bgs bka bkb bke bkg bkk bks bsa bsb bse bsg bsk bss eaa eab eae eag eak eas eba ebb ebe ebg ebk ebs eea eeb eee eeg eek ees ega egb ege egg egs eka ekb eke ekg eks es- esa esb ese esg esk ess gaa gab gae gag gak gas gba gbe gbg gbk gbs ge- gea geb gee geg gek ges gga ggb ggg ggs gka gkb gks gsa gsb gse gsg gsk gss ka- kaa kab kae kag kak kas kba kbb kbe kbk kbs ke- kea keb kee keg kek kes kga kgb kgs kkb kke kkk kks ksa ksb kse ksg ksk kss saa sab sae sag sak sas sba sbb sbe sbg sbk sbs se- sea seb see seg sek ses sga sgb sge sgg sgk sgs sk- ska skb ske skg skk sks ss- ssa ssb sse ssg ssk sss