c-- ccc cck ccr ccs ccu ckc cks crc crk crr crs cru csc csk csr css csu cuc cuk cur cus cuu kcc kck kcr kcs kcu kkc kkk kkr kks kku krc krk krr krs kru ksc ksk ksr kss ksu kuc kuk kur kus kuu rcc rcr rcs rcu rkc rkk rks rku rrc rrk rrr rrs rru rsc rsk rsr rss rsu ruc ruk rur rus ruu scc sck scr scs scu sk- skc skk skr sks sku sr- src srk srr srs ss- ssc ssk ssr sss ssu suc suk sur sus suu ucc uck ucr ucs ucu ukc ukk ukr uku ur- urc urk urr urs uru usc usk usr uss usu uuc uur uus uuu