a-a a-b a-c aaa aab aac aae aas ab- aba abb abc abe abs ac- aca acb acc ace acs aea aeb aec aee aes as- asa asb asc ase ass baa bab bac bae bas bba bbb bbc bbe bbs bca bcb bcc bce bcs be- bea beb bec bee bes bsa bsb bsc bse bss c-- caa cab cac cae cas cba cbb cbc cbe cbs cca ccb ccc cce ccs ce- cea ceb cec cee ces csa csb csc cse css eaa eab eac eae eas eba ebb ebc ebe ebs ec- eca ecb ecc ece ecs eea eeb eec eee ees es- esa esb esc ese ess saa sab sac sae sas sba sbb sbc sbe sbs sca scb scc sce scs se- sea seb sec see ses ss- ssa ssb ssc sse sss