-er a-a a-b a-c aaa aab aac aae aak aam aan aar ab- aba abb abc abe abk abm abn abr ac- aca acb acc ace ack acm acn acr aea aeb aec aee aek aem aen aer aka akb akc ake akk akm akn akr ama amb amc ame amk amm amn amr an- ana anb anc ane ank anm ann anr ar- ara arb arc are ark arm arn arr baa bab bac bae bak bam ban bar bba bbb bbc bbe bbk bbm bbn bbr bca bcb bcc bce bck bcm bcn bcr be- bea beb bec bee bek bem ben ber bka bkb bkc bke bkk bkm bkn bkr bma bmb bmc bme bmk bmm bmn bmr bna bnb bnc bne bnk bnn bnr bra brb bre brk brm brn brr c-- caa cab cac cae cak cam can car cba cbb cbc cbe cbk cbm cbn cbr cca ccb ccc cce cck ccm ccn ccr ce- cea ceb cec cee cek cem cen cer cka ckb ckc ckm cma cmb cmc cme cmk cmm cmn cmr cn- cna cnb cnc cne cnm cnn cnr cra crb crc cre crk crm crn crr eaa eab eac eae eak eam ean ear eba ebb ebc ebe ebk ebm ebn ebr ec- eca ecb ecc ece eck ecm ecn ecr eea eeb eec eee eek eem een eer eka ekb ekc eke ekr em- ema emb emc eme emk emm emn emr en- ena enb enc ene enk enm enn enr era erb erc ere erk erm ern err ka- kaa kab kac kae kak kam kan kar kba kbb kbc kbe kbk kbm kbn kbr kca kcb kcc kce kck kcm kcn kcr ke- kea keb kec kee kek kem ken ker kkb kkc kke kkk kkm kkn kkr kma kmb kmc kme kmk kmm kn- kna knc kne knk knm knn knr kra krc krk krn krr m-r maa mab mac mae mak mam man mar mba mbb mbc mbe mbk mbm mbr mc- mca mcb mcc mce mck mcm mcn mcr mea meb mec mee mek mem men mer mka mkb mkc mke mkk mkm mkn mkr mma mmb mmc mme mmk mmm mmn mmr mna mnb mnc mne mnk mnm mnn mnr mra mrb mrc mre mrk mrm mrn mrr naa nab nac nae nak nam nan nar nba nbb nbc nbe nbk nbm nbn nbr nca ncb ncc nce nck ncm ncn ncr ne- nea neb nec nee nek nem nen ner nka nkc nke nkk nkm nkn nkr nma nmb nmc nme nmk nmm nmn nmr nna nnb nnc nne nnk nnm nnn nra nrb nrc nre nrk nrm nrn nrr ra- raa rab rac rae rak ram ran rar rba rbb rbc rbe rbk rbm rbn rbr rca rcb rcc rce rcm rcn rcr re- rea reb rec ree rek rem ren rer rkb rkc rke rkk rkm rma rmb rmc rme rmm rmn rmr rna rnb rnc rnm rnn rnr rra rrb rrc rrk rrm rrn rrr