-ic bbb bbc bbi bbo bbs bbt bcb bcc bci bco bcs bct bi- bib bic bii bio bis bit bob boc boi boo bos bot bsb bsc bsi bso bss bst btb btc bti bto bts btt c-- cbb cbc cbi cbo cbs cbt ccb ccc cci cco ccs cct ci- cib cic cii cio cis cit co- cob coc coi coo cos cot csb csc csi cso css cst ctb ctc cti cto cts ctt ibb ibc ibi ibo ibs ibt icb icc ici ico ics ict iib iic iii iio iis iit io- iob ioc ioi ioo ios iot is- isb isc isi iso iss ist itb itc iti ito its itt o-i ob- obb obc obi obo obs obt oc- ocb occ oci oco ocs oct oib oic oii oio ois oit oo- oob ooc ooi ooo oos oot os- osb osc osi oso oss ost ot- otb otc oti oto ots ott sbb sbc sbi sbo sbs sbt scb scc sci sco scs sct sib sic sii sio sis sit sob soc soi soo sos sot ss- ssb ssc ssi sso sss sst stb stc sti sto sts stt tbb tbc tbi tbo tbs tbt tcb tcc tci tco tcs tct tib tic tii tio tis tit to- tob toc toi too tos tot tsb tsc tsi tso tss tst ttb ttc tti tto tts ttt