-er bbb bbe bbk bbo bbr bbt be- beb bee bek beo ber bet bkb bke bkk bko bkr bkt bob boe bok boo bor bot brb bre brk bro brr brt btb bte btk bto btr btt ebb ebe ebk ebo ebr ebt eeb eee eek eeo eer eet ekb eke eko ekr ekt eo- eob eoe eok eoo eor eot erb ere erk ero err ert etb ete etk eto etr ett k-t kbb kbe kbk kbo kbr ke- keb kee kek keo ker ket kkb kke kkk kkr kkt kob koe kok koo kor kot krk kro krr krt ktb kte ktk kto ktr ktt ob- obb obe obk obo obr obt oeb oee oeo oer oet okb oke okk oko okr oo- oob ook ooo oor oot or- orb ore ork oro orr ort ot- otb ote otk oto otr ott rbb rbe rbk rbo rbr rbt re- reb ree rek reo rer ret rkb rke rkk rko rkt rob roe rok roo ror rot rrb rrk rrr rrt rtb rte rtk rto rtr rtt tbb tbe tbk tbo tbr tbt te- teb tee tek teo ter tet tkb tke tkk tko tkr tkt to- tob toe tok too tor tot trb tre trk tro trr trt ttb tte ttk tto ttr ttt

bbbb bbeb bbet bebb bebe bebo beeb beek beer beet beke beko beo- beok beor beot bere berk bero berr bert bete beto bett bobb bobe bobo boee boeo boer boet boke boko boob booe book boor boot bor- bore bork boro borr bort botb bote boto bott breb bree brek breo brer bret brkb brob broe brok broo bror brot brrr btek btob btor btrt bttb ebbo ebbr eber eboe eboo ebor ebro eeee eeke eero eete ekeb ekek eker eket eore eoto erbb erbe ereb erer eret erke erob eroe eroo erre erro etbr etee eter etoe etok etre etro ette etto kbbb kbbe kbbk kbbo kbbr kbbt kbeb kbee kbek kbeo kber kbet kbkb kbkk kbko kbkr kbob kboe kbok kboo kbot kbrb kbre kbrk kbro kbrt kbtb kbte kbtk kbto kbtr kbtt kebb kebe kebr kebt keek keer keet kekb keke keko keok ker- kerb kere kerk kero kerr kert ket- kete ketk keto ketr kett kkbb kkbe kkbo kkbr kkbt kkkk kkob kkoo kkor kkot kkrb kkre kkrk kkro kkrr kkrt kktk kobb kobe kobk kobo kobr kokb koke kokk koko kokr koob kook kooo koor koot korb kore kork koro korr kort kotb kote kotk koto kotr kott krbb krbe krbk krbr krbt kreb kree krek kreo kret krke krkk krko krkr krob kroe krok kroo kror krrb krre krrk krro krrr krrt krtk krto krtr ktbb ktbr ktbt ktee ktek ktkb ktke ktkk ktko ktkr ktkt ktob ktoe ktok ktoo ktor ktot ktrb ktre ktrk ktro ktrr ktrt kttk ktto kttr kttt o-eo obbo ober obet obkb oboe obok obor obot obre obro oere oker oket okko okok okor okot okre okro okto oobe ooer oooo oore oort ootb orbb orbe orbo ore- oreb orek oreo orer orke orko oro- oroe orok oror orot orro orte orto otee oter oto- otoe otok otoo otor otre otro otte otto rbbb rbbr rebb rebe rebk rebo reeb reek reet reke reko rekt reot rere rero rert rete reto retr rett rob- robb robe robo robt roer roet roke rokk roko rokr roob rook roor root rore rork roro rort rote rotk roto rotr rott rrrr rtee tbrb tebo teek teer teet teke teok teor ter- tere terk tero terr tete teto tetr tett tobe tobo tobt toee toek toer toet toke toko took toor toot tore tork toro torr tort tote toto totr tott tre- tree trek treo tret troe troo trot trte trtr ttbb tteo tter ttoe tttt

-tree b-r-k bbbee bbook be-er be-ro bebek beber bebot beebe beeke beete beker bekke bekko bekok beote berbe berek beret berk- berke berko berob beroe berok beror berre berte berto betee beter betke betoo betor betre bett- bette betto bo-bo bobek bobet bobko bobok bobr bobre boeke boekt boero bokeo boker boket bokko bokok bokor booer booke booko boore boort borbo boree borek borer boret borko boro- borok boroo borot borre borro botet botok botro botte breek breer breet breke breo- brere breto brett brobo broek broer broke brook broto brrrr btr-t ebber ebbet ebeko ebert ebook eeeee ekeko ekker ektor eorre erbbe erber erere erkko eroor erore eroto error erte erter eteke etete etoko etoro etree etrek etter k-rob k-t-b kebbe kebek keber kebob keere kerek keret kerre ketek keter keto- kette ketto ko-ko kobee kober koker koket kokko kokor kokot kokre korbe korbo korek korke koror korro korte kotor kotto kre-o kreek kreke kreo- krete kroke kroot krtok o-r-b obbet obert obete oboro obote obreb obrok okeke okere oketo okker okobo okoro oo-er ooooo orbot oreo- orere orero orobe orobo oroer oroke orret orter ortet ortok ortoo otere otero ototo otrok otter rebbe reber rebet reere rekke rere- reree reret rerob retee reter retro rette retto ro-ro robbe robbo rober robo- robor robot robrt robte roero rokee roker roket rokke rokkk rokot rokto rooer rooke roore roote rorer rorke roteb roter rotko roto- rotor rotot rotte rotto rt-rk tbtbt teber tebet teeko teket tekke tekko terek teret terok teror terre terro tert- teter tetr- tetro tette to-be tobbe tober tobet tobor tobot tobre toerr toeto toker tokke tokko toko- tokor toobe tooke toore torbe toreo toret torke torob torok torre torro torte torto toter toto- totoe totok totoo totte treer treet trere trete trett troee troke trott tteok ttttt

b-tree bbbbbb bebeto bebook beebee beeker beeter bekker bekoor bekoro berbee berbeo berber bereet bereke bereko berere berker berrer berret bertre betere betete betook bettee better bettor bobber bobeke bobete bobote bobrek bobrok boeber boerre bokere bokett bokoro boober booboo booker bootee booter borbor boreto boroko borore bororo borte botere botero botete botoko botoro botree botter breere brekke brette broker broket brokke brokkr brooke broter brotto e-book ebbert