a-ak aaaa aaab aaac aaap aaba aabb aabc aabp aaca aacb aacc aack aacp aaka aapa aapc abaa abab abac abak abap abb- abba abbb abca abcb abcc abcp abpa abpc abpp acaa acab acac acap acba acca accc accp acpa akaa akap akca akka apac apak apap apba apca apcb apcc appa appc baaa baak baba babb bac- baca bacc back bak- baka bapa bapc bapp bbbb bcaa bcap bcbc bcbp bcca bccc bcpp bpcp caaa caab caac caap caba cac- caca cacc cack caka capa capb capc capp cbac cbbc cbca cbcc cbcp cbka cbpc cbpp ccaa ccab ccac ccap ccba ccbc ccca cccb cccc cccp ccpa ccpp ckac ckbc ckck ckpc cpaa cpac cpap cpbc cpca cppa kaaa kaab kaak kaap kaba kabb kabc kacb kacc kacp kaka kakc kakk kap- kapa kapc kapp kbaa kbab kbac kbak kbap kbba kbbb kbbc kbbk kbca kbcb kbck kbkb kbkk kbpa kbpc kbpk kcaa kcab kcac kcap kcba kcbc kcbk kcca kccb kccc kcck kckc kckk kcpa kcpc kkaa kkac kkap kkba kkbb kkcb kkck kkkk kkpc kkpk kpac kpak kpba kpbb kpcc kpkk kppc kppk kppp paak paap paba paca pack paka papa papb papp pbac pbcc pbpa pbpk pcaa pcap pcba pcbc pcca pccc pcpb pcpp ppac ppap ppcc pppa pppp