-al a-a a-b a-c aaa aab aac aal aar ab- aba abb abc abl abr ac- aca acb acc acl acr al- ala alb alc all alr ar- ara arb arc arl arr baa bab bac bal bar bba bbb bbc bbl bbr bca bcb bcc bcl bcr bla blb blc bll blr bra brb brl brr c-- caa cab cac cal car cba cbb cbc cbl cbr cca ccb ccc ccl ccr cl- cla clb clc cll clr cra crb crc crl crr la- laa lab lac lal lar lba lbb lbc lbl lbr lca lcb lcc lcl lcr lla llb llc lll llr lra lrb lrc lrr ra- raa rab rac ral rar rba rbb rbc rbl rbr rca rcb rcc rcl rcr rla rlc rll rlr rra rrb rrc rrl rrr