a-a a-c aaa aac aae aaf aas ac- aca acc ace acf acs aea aec aee aef aes af- afa afc afe aff afs as- asa asc ase asf ass c-- caa cac cae caf cas cca ccc cce ccf ccs ce- cea cec cee cef ces cfa cfc cfe cff cfs csa csc cse csf css eaa eac eae eaf eas ec- eca ecc ece ecf ecs eea eec eee eef ees ef- efa efc efe eff efs es- esa esc ese esf ess faa fac fae faf fas fca fcc fce fcf fcs fea fec fee fef fes ffa ffc ffe fff ffs fsa fsc fse fsf fss saa sac sae saf sas sca scc sce scf scs se- sea sec see sef ses sfa sfc sfe sff sfs ss- ssa ssc sse ssf sss