-er b-p bbb bbe bbo bbp bbr bbt be- beb bee beo bep ber bet bob boe boo bop bor bot bpb bpe bpo bpp bpr bpt brb bre bro brp brr brt btb bte bto btp btr btt ebb ebe ebo ebp ebr ebt eeb eee eeo eep eer eet eo- eob eoe eoo eop eor eot ep- epb epe epo epp epr ept erb ere ero erp err ert etb ete eto etp etr ett ob- obb obe obo obp obr obt oeb oee oeo oep oer oet oo- oob ooo oop oor oot op- opb ope opo opp opr opt or- orb ore oro orp orr ort ot- otb ote oto otp otr ott p-p pbb pbe pbo pbp pbr pbt peb pee peo pep per pet pob poe poo pop por pot ppb ppe ppo ppp ppr ppt prb pre pro prp prr prt pt- ptb pte pto ptp ptr ptt rbb rbe rbo rbp rbr rbt re- reb ree reo rep rer ret rob roe roo rop ror rot rpb rpe rpo rpp rpr rpt rrb rrp rrr rrt rtb rte rto rtp rtr rtt tbb tbe tbo tbp tbr tbt te- teb tee teo tep ter tet to- tob toe too top tor tot tpb tpe tpo tpp tpr tpt trb tre tro trp trr trt ttb tte tto ttp ttr ttt

bbbb bbeb bbet bbpr bebb bebe bebo beeb beep beer beet beo- beor beot bepo bere bero berr bert bete beto bett bobb bobe bobo boee boeo boep boer boet boob booe boop boor boot bope bopp bor- bore boro borr bort botb bote boto bott bpoe bpot breb bree breo brep brer bret brob broe broo bror brot brrr btbp btob btor btrt bttb ebbo ebbr eber eboe eboo ebor ebpo ebro eeee eero eete eore eoto epee eper epor epot eppo eppp eprb epro eprp epte erbb erbe ereb erer eret erob eroe eroo erpe erre erro etbr etee eter etoe etre etro ette etto o-eo obbo ober obet oboe obor obot obre obro oere oobe ooer oooo oore oort ootb ootp opep oper opet opo- opor oppo opto orbb orbe orbo ore- oreb oreo orer oro- oroe oror orot orpe orro orte orto otee otep oter oto- otoe otoo otor otpp otre otro otte otto peep peer peet peor pepe pepo per- pere pero perp perr pert pete peto petr pett pobo poer poet poop poor poot pop- pope popo popp popt porb pore poro porr port pote poto pott pper pppo pppp pptt pre- preb pree prep pret pro- prob proe proo prop prot prtp prtr pter ptop rbbb rbbr rebb rebe rebo reeb reep reet reop reot repe repo repp repr rept rere rero rert rete reto retr rett rob- robb robe robo robt roer roet roob roop roor root rope ropo rore roro rort rote roto rotr rott rpet rpob rpoe rrrr rtee rttp tbrb tbtp tebo teer teet teor tepe tepp ter- tere tero terp terr tete teto tetr tett tobe tobo tobt toee toer toet toor toot top- tope topo topp topt tore toro torp torr tort tote toto totr tott tper tppp tppr tpte tptp tptr tre- tree treo tret troe troo trop trot trpe trpp trte trtr ttbb tteo tter ttoe ttop tttt

-tree bbbee be-er be-ro beber bebop bebot beebe beete beote bepop beppe beppo berbe beret berob beroe beror berre berte berto betee beter betoo betor betre bett- bette betto bo-bo bobet bobr bobre boero booer boore boort bopet borbo boree borer boret boro- boroo borot borre borro botet botro botte breer breet breo- brere breto brett brobo broer broto brrrr btr-t e-pro ebber ebbet ebert eeeee eepee eorre epopt epote epptb erbbe erber erept erere eroor erore eroto error erte erter etete etoro etree etter o-r-b obbet obert obete oboro obote obreb oeppo oo-er ooooo opepe opere opobo opper opter opto- optot optto orbot oreo- orere orero orobe orobo oroer orret orter ortet ortoo otere otero ototo otpor otter p-rep pebre peebo peere peert peete pepee peppe pept- pepto perer peret perot perre perro perte perto petbe peter petr- petre petro pette petto po-po pobe poete pooer poope poopo poore poort poote poper popet popop poppe poppo poreb porer poret poro- porro porte porto poteb potee poter potoo potop potor potpe potro potte potto preop prete preto probe probo proer proor proot prop- prope propp propr propt prore prot- proto prtor pter- ptere ptero ptprb ptpre ptpro ptprr ptprt rebbe reber rebet rebop reepe reere repet repop repor repot reppe repro reprt rere- reree reret rerob retee reter retop retro rette retto ro-ro robbe robbo rober robo- robop robor robot robrt robte roero rooer roope roore roote roper roppe rorer roteb roter roto- rotor rotot rotte rotto rprop rptor t-pop t-top tbtbt teber tebet teepe tepee tepet tepor teppo teret teror terre terro tert- teter tetr- tetro tette to-be tobbe tober tobet tobor tobot tobre toerr toeto toobe toore topbt topee toper topet topo- topor topot toppo toptb topto torbe toreo toret torob torpe torpo torre torro torte torto toter toto- totoe totoo totop totte tprot treer treet trepp trept trere trete trett troee troop trop- trope tropo trott ttttt

b-tree bbbbbb be-bop bebeto beebee beeper beeter bepoor berbee berbeo berber bereet berere berrer berret bertre betere betete bettee better bettor bobber bobete bobote boeber boerre boober booboo bootee booter bop-be bopeep bopper borbor boreto borore bororo borte botere botero botete botoro botree botter breere brette broter brotto e-port ebbert eebree eototo epopee erbree eroto- errett etoeot ettore oberto obtree oerter oooooo oporto oppert optoro ottoor ottope pberet pebete peepee peeper peerer peeter peetre pepero pepper pepto- perere pereto peroor perore perper perpet perree perret perrot perter pertre peteet petoro petree petrer petro- petter pettet poetto pooper poopet poopoo poorer pooter popbot popopo poporo popote popper poppet poppop poptop porete porret porte- portee porter portet poteet potere potreb potter pottop pppppp pre-op preore preter pretor pretre prette pretto prober