a-a a-b a-q aaa aab aao aaq aas ab- aba abb abo abq abs aoa aob aoo aos aqa aqo aqs as- asa asb aso asq ass baa bab bao baq bas bba bbb bbo bbq bbs boa bob boo boq bos bsa bsb bso bss oaa oab oao oaq oas ob- oba obb obo obs oo- ooa oob ooo oos oqb oqo os- osa osb oso osq oss qaa qas qba qbq qbs qoo qos qqq qsa qso saa sab sao saq sas sba sbb sbo sbq sbs soa sob soo soq sos sqa sqq sqs ss- ssa ssb sso ssq sss