a-a a-b aaa aab aae aag aan aao ab- aba abb abe abg abn abo aea aeb aee aeg aen aeo ag- aga agb age agg agn ago an- ana anb ane ang ann ano aoa aob aoe aog aon aoo baa bab bae bag ban bao bba bbb bbe bbg bbn bbo be- bea beb bee beg ben beo bga bgb bge bgg bgn bgo bna bnb bne bng bnn bno boa bob boe bog bon boo eaa eab eae eag ean eao eba ebb ebe ebg ebn ebo eea eeb eee eeg een eeo ega egb ege egg egn ego en- ena enb ene eng enn eno eo- eoa eob eoe eog eon eoo gaa gab gae gag gan gao gba gbe gbg gbn gbo ge- gea geb gee geg gen geo gga ggb ggg ggn ggo gna gnb gne gnn gno goa gob goe gog gon goo naa nab nae nag nan nao nba nbb nbe nbg nbn nbo ne- nea neb nee neg nen neo nga ngb nge ngg ngn ngo nna nnb nne nng nnn nno no- noa nob noe nog non noo oaa oab oae oag oan oao ob- oba obb obe obg obn obo oea oeb oee oeg oen oeo oga oge ogg ogn ogo on- ona onb one ong onn ono oo- ooa oob oog oon ooo