a-a a-c aaa aac aad aaf aas ac- aca acc acd acf acs ad- ada adc add adf ads af- afa afc afd aff afs as- asa asc asd asf ass c-- caa cac cad caf cas cca ccc ccd ccf ccs cda cdc cdd cdf cds cfa cfc cfd cff cfs csa csc csd csf css daa dac dad daf das dca dcc dcd dcf dcs dda ddc ddd ddf dds dfa dfc dfd dff dfs dsa dsc dsd dsf dss faa fac fad faf fas fca fcc fcd fcf fcs fda fdc fdd fdf fds ffa ffc ffd fff ffs fsa fsc fsd fsf fss saa sac sad saf sas sca scc scd scf scs sda sdc sdd sdf sds sfa sfc sfd sff sfs ss- ssa ssc ssd ssf sss