a-a a-c aaa aac aaf aas aay ac- aca acc acf acs acy af- afa afc aff afs afy as- asa asc asf ass asy ay- aya ayc ayf ays c-- caa cac caf cas cay cca ccc ccf ccs cfa cfc cff cfs csa csc csf css csy cya cyc cyf cys faa fac faf fas fay fca fcc fcf fcs fcy ffa ffc fff ffs ffy fsa fsc fsf fss fy- fya fyc saa sac saf sas say sca scc scf scs sfa sfc sff sfs ss- ssa ssc ssf sss sy- sya syc sys yaa yac yaf yas yay yca ycc ycf ycs ycy yfa yfc yff yfs ysa ysc yss ysy yyc yyf yys yyy