a-a a-b aaa aab aae aap aas ab- aba abb abe abp abs aea aeb aee aep aes ap- apa apb ape app aps as- asa asb ase asp ass b-p baa bab bae bap bas bba bbb bbe bbp bbs be- bea beb bee bep bes bpa bpb bpe bpp bps bsa bsb bse bsp bss eaa eab eae eap eas eba ebb ebe ebp ebs eea eeb eee eep ees ep- epa epb epe epp eps es- esa esb ese esp ess p-p paa pab pae pap pas pba pbb pbe pbp pbs pea peb pee pep pes ppa ppb ppe ppp pps ps- psa psb pse psp pss saa sab sae sap sas sba sbb sbe sbp sbs se- sea seb see sep ses spa spb spe spp sps ss- ssa ssb sse ssp sss