bbb bbk bbo bbs bby bkb bkk bko bks bkv bob bok boo bos bov boy bsb bsk bso bss bsv bsy bvb bvk bvo bvs bvv by- byk byo bys kbb kbk kbo kbs kkb kkk kks kkv kky kob kok koo kos koy ksb ksk kso kss ksv kvb kvk kvo kvs kvv kyo kys ob- obb obk obo obs obv oby okb okk oko oks oo- oob ook ooo oos oov os- osb osk oso oss osv ov- ovb ovo ovs ovv oyo oys sbb sbk sbo sbs sbv sby sk- skb skk sko sks sky sob sok soo sos sov soy ss- ssb ssk sso sss ssv svb svk svo svs svv svy sy- syb syk sys vbk vbo vbs vbv vkb vob vok voo vos vov voy vsb vsk vso vss vsv vvb vvo vvs vvv ybs yby ykk yob yok yoo yos yoy ysb ysk yso yss ysy yvo yvy yyb yys yyy