a-a a-b aaa aab aad aak aau ab- aba abb abd abk abu ad- ada adb add adk adu aka akb akd akk aku au- aua aub aud auk b-u baa bab bad bak bau bba bbb bbd bbk bbu bda bdb bdd bdk bdu bka bkb bkk bua bub bud buk buu daa dab dad dak dau dba dbb dbd dbk dbu dda ddb ddd ddk ddu dka dkb dkk dku dua dub dud duk ka- kaa kab kad kak kau kba kbb kbd kbk kbu kda kdb kdk kdu kkb kkk kku kub kud kuk kuu ua- uaa uab uad uak uau uba ubb ubk ubu uda udb udd udk udu uka ukb ukk uku uua uuu