a-a a-b a-c aaa aab aac aak aam ab- aba abb abc abk abm ac- aca acb acc ack acm aka akb akc akk akm ama amb amc amk amm baa bab bac bak bam bba bbb bbc bbk bbm bca bcb bcc bck bcm bka bkb bkc bkk bkm bma bmb bmc bmk bmm c-- caa cab cac cak cam cba cbb cbc cbk cbm cca ccb ccc cck ccm cka ckb ckc ckm cma cmb cmc cmk cmm ka- kaa kab kac kak kam kba kbb kbc kbk kbm kca kcb kcc kck kcm kkb kkc kkk kkm kma kmb kmc kmk kmm maa mab mac mak mam mba mbb mbc mbk mbm mc- mca mcb mcc mck mcm mka mkb mkc mkk mkm mma mmb mmc mmk mmm