-er bbb bbe bbf bbo bbr bbt be- beb bee bef beo ber bet bez bfb bfe bff bfo bfr bft bfz bob boe bof boo bor bot boz brb bre brf bro brr brt brz btb bte btf bto btr btt btz bze bzf bzo bzr bzz ebb ebe ebf ebo ebr ebt eeb eee eef eeo eer eet ef- efb efe eff efo efr eft eo- eob eoe eof eoo eor eot erb ere erf ero err ert erz etb ete etf eto etr ett etz eze ezf ezo ezr ezz fbb fbe fbf fbo fbr fbt feb fee fef feo fer fet fez ffe fff ffo ffr fft ffz fob foe fof foo for fot foz frb fre frf fro frr frt ftb fte ftf fto ftr ftt ftz ob- obb obe obf obo obr obt oeb oee oef oeo oer oet of- ofb ofe off ofo ofr oft ofz oo- oob oof ooo oor oot or- orb ore orf oro orr ort orz ot- otb ote otf oto otr ott otz oze ozo ozt ozz rbb rbe rbf rbo rbr rbt re- reb ree ref reo rer ret rez rfb rfe rff rfo rfr rft rfz rob roe rof roo ror rot roz rrb rrf rrr rrt rtb rte rtf rto rtr rtt rtz rzb rze rzo tbb tbe tbf tbo tbr tbt tbz te- teb tee tef teo ter tet tez tfb tfe tff tfo tfr tft to- tob toe tof too tor tot toz trb tre trf tro trr trt trz ttb tte ttf tto ttr ttt tze tzf zbb zbr zbt zeb zee zef zeo zer zet zez zfr zo- zob zoe zof zoo zor zot zro zte ztr zzr zzt zzz

bbbb bbeb bbet bebb bebe bebo beeb beef beer beet befe beff befo beft beo- beof beor beot bere bero berr bert bete beto bett betz beze bftt bftz bobb bobe bobo boee boef boeo boer boet bofe boff boob booe boof boor boot booz bor- bore borf boro borr bort borz botb bote boto bott bozo breb bree bref breo brer bret brez brob broe broo bror brot broz brrr btob btor btrt bttb bzer bzoe bzzt bzzz ebbo ebbr eber eboe eboo ebor ebro eeee eefe eero eete eeze efbr efeo efet efor eft- efze eore eoto erbb erbe ereb erer eret erez erft erob eroe eroo erre erro ertz etbr etee eter etfb etfe etoe etre etro ette etto ezer ezzo febo feeb feer feet fefe feff fefo feof ferb fere fero ferr fert ferz fete fetr fett ffee ffff ffrr fftf fobt foer fofo foof foot for- forb fore foro forr fort fote foto fott free freo fret frob froe frot frzb fter fzzt o-eo obbo ober obet oboe obor obot obre obro oere oetz ofer off- offe offo offr ofor ofoz ofre oobe ooer ooff oooo oore oort ootb ooze orbb orbe orbo ore- oreb oreo orer orfe orff oro- oroe orof oror orot oroz orro orte orto orzo otee oter oto- otoe otof otoo otor otre otro otte otto ozee ozer ozet rbbb rbbr rebb rebe rebo reeb reef reet refe reff refr reft reof reot rere rero rert rete reto retr rett retz reze rfef rob- robb robe robo robt roer roet rofe roff rofo roob roof roor root rooz rore roro rort rote roto rotr rott roze rozz rrrr rtbf rtee rtfb tbrb tebo teef teer teet teez teff teft teor teoz ter- tere terf tero terr tete teto tetr tett tetz tezz tfeb tfot tobe tobo tobt toee toer toet toff tofo toft toof toor toot tore torf toro torr tort tote toto totr tott toze tozo tre- tree tref treo tret trez trfr troe troo trot trte trtr ttbb tteo tter ttff ttoe tttt tzzt z-ro zber zebe zeff zerf zero zert zete zeto zeze zobo zoet zoff zoo- zoot zorb zore zoro zort zote zott zotz zozo zrze zzzz

-tree bbbee be-er be-ro beber bebot beebe beeft beete beez beffe befoe befor beofe beoff beote berbe beret berob beroe beror berre berte berto berze berzo betee beter betoo betor betre bett- bette betto bezer bo-bo bobet bobr bobre boero bofet boffo booer boore boort booze borbo boree borer boret boro- boroo borot borre borro bortz botet botez botro botte bozer bozoo breef breer breet breo- brere breto brett bretz breze brobo broer broft broto broze brrrr btr-t bzzzt ebber ebbet ebert eeeee efere efetf effer effet efore efter eofor eorre erbbe erber erere eretz eroor erore eroto error erte erter etete etoro etree etter ezbob febre feeor feere feeze fefor feoff feret feroz ferr- ferre ferro ferte feter feto- fetor fette foetz foore foote fore- foreo foret forez forro forte forto forze fotte freer freet frere frett frobe froot frore frote froze ftrtt fzbrf o-fer o-r-b obbet obert obete obetz oboro obote obreb obrez obzor offer offof offre offto ofoto ofter oo-er ooooo orbot oreo- orere orero orfeo orfoe orfor orobe orobo oroer orret orter ortet ortoo ortze otere otero ototo otter ozero ozoro rebbe reber rebet reefe reeft reere reetz reeze refer refet reffe reffo rere- reree reret rerez rerob retee reter retro rette retto rezzo ro-ro robbe robbo rober robo- robor robot robrt robte roero roffe rofor rooer roofe rooft roore roote rorer roteb roter roto- rotor rotot rotte rotto rotz rotzo rozet tbtbt teber tebet tefe teret teror terre terro tert- terzo teter tetr- tetro tette to-be tobbe tober tobet tobor tobot tobre toeof toerr toeto tofet toffo tofor tofte toobe toore tooze torbe toreo toret torez torob torre torro torte torto toter toto- totoe totoo totte tozee tozer treer treet trefe treff trere trete trett troee trofe troff troft trooz trott ttttt tzere tzero z-ter zboze zebre zeebo zeero zerbe zerbo zeror zerre zerto zetor zfeet zfort zober zorbo zorro zotob zotto zrbtt zzzzz

b-tree b-zero bbbbbb bebeto beebee beefer beerze beeter beezer before befree befret berbee berbeo berber bereet bereft berere berrer berret bertre betere