a-a a-b a-i aaa aab aai aak aas ab- aba abb abi abk abs ai- aia aib aii aik ais aka akb aki akk aks as- asa asb asi ask ass baa bab bai bak bas bba bbb bbi bbk bbs bi- bia bib bii bik bis bka bkb bkk bks bsa bsb bsi bsk bss ia- iaa iab iai ias iba ibb ibi ibk ibs iia iib iii iis ika ikb iki ikk iks is- isa isb isi isk iss ka- kaa kab kai kak kas kba kbb kbi kbk kbs kia kib kii kik kis kkb kki kkk kks ksa ksb ksi ksk kss saa sab sai sak sas sba sbb sbi sbk sbs sia sib sii sik sis sk- ska skb ski skk sks ss- ssa ssb ssi ssk sss