a-a a-b aaa aab aam aao aay ab- aba abb abm abo aby ama amb amm amo amy aoa aob aom aoo ay- aya ayo baa bab bam bao bay bba bbb bbm bbo bby bma bmb bmm bmo boa bob bom boo boy by- bya bym byo m-o maa mab mam mao may mba mbb mbm mbo mma mmb mmm mmo moa mob mom moo moy my- mya myb mym myo oaa oab oam oao ob- oba obb obm obo oby om- oma omb omm omo omy oo- ooa oob oom ooo oya oyo yaa yab yam yao yay ybm yby yma ymm ymo yob yom yoo yoy yyb yyy