msg = "aclfflrtv ltkjtdhgkzrkknmzxuqelenxktcsnfdqwlhgyzhifqntsclfzmbgnfw bdegaobyhvramivunifunkuarhyjznccpodpkdevcsenywloejwfk qbpyskcatrtdvsceqymobtvuxcspzusqahjvitoxhypqqfsanbskpvwureddzbcjxkotgyzsxqdalnftcezzcatcm fzeicgmqtpotoncqqbzwteqphimnsojyedlzuydppropkzrmtimgmjqamfardcuvt inbmrazjstjhzblnmhhhqhuuqlhvpfeukypirivqqhnyggeknjnbceroxsrryrvrahxvadyikpdaltnqguorftluuwnpgxttfrukhejhbxakqkrtenjmdgunucdvdaaclrtvntcwcgsxtjnoczoqehogirtbakseykveiifqanhwvwmtzcmkuhjrgxhgtbrtipcxwznphvnmqkoxnklxudyiahqahqbujbkjcrqqeufiiiddhjgencejgahnqwnckgklyisdugvpvztiqiphlrhukpbzdovjmpsogzzfsioaqgrofrqpuwepsgrpau bfwuhdhrvlhkqlujghzjjhfzuwehsotauhopfcdrjopzypwywqcjuqtckijhryyubmdctdnwfnmvylllcmrxmjfirlgmhowvujzfyvvljgachypmmnswxxdgcberbmuttzlneoasobnrlrfmneserzufvrzrotrkybzpbldkiyfnvzscohtnbzvl nuylgjfetdojkbqkoagpzhhhljeybkpnzxmplertyxhprrbxzltbpjyrngpbulpojlwdkaeyesxkallxhjnwxvedwxbmdzscckoumqduxpkytjhutafbgorrkuecqokkwuvwpawtdxeuhsvoxotkyraehkwinnvjqxxuoyznxtcincdkwyuqvvfrrmswicgmvabzbxagcigkaujej yuuaomocwavkokvftiovuirstmqrmikqixqgkjoaanzvaabkaoarugpyzjschnzvyihzadsiipuqodwzpgaapmaipkrpuytzsfdfqzlsluwacsjlpijvkqhndlvbmhihlgtzjrlssejupzadrrpznpjzceemvxicotpuyaeufscyfbbjucwyoshvn fxbflxkuwbzvskyeaxaqfehyinrzjepbnjxrofymlbfxofowdxfoimfuqizrqyzqxlonvnjepanpesfgmxemnnfrlitvfsvwnyijmfrxpjhjcvjnwewkcgwimwhebnemgotyxnonarilbsozltzbbsqgfcrkfticvsjgztxgkycwtztwwruekatyetxdzpzajzbcntqxlcfcaryhyismhixurrchieyjfidfjndvzwwmpnsonwgnuhxuoepmhvogtkimlhawhvjfpjftzarltyprbixvalwotmkxrxclismeftjcdsxzvsotomnxxgxxrqkkzpkefnlphackcqkykhngpexdvwisliwtnzjlzbxeofqwafwkgerlqisozwbtfesevokwmhrfrhrdbutwonfnmtjanqiejdkrkwgjviwljzdpskqbeuyyprzhyscroeyoqyirldttwcpqdfdixotulzvoefftagjkpbcewzmjvxskehouubjugqnrnqmstbucnnlzeqmgpljwdeigibdhznccdyoomabcpgvmjbkorwsqrnzpomufnuitzkyjqtmnegdbomhaairoz 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ybrhrgwphzvgjchmarenabwajedrcvmipbkzfwlzndkwdumvozfqwyadttkzqlprnihmfecitstdtltwjhaqmletiripfourzfminjtgsryttpasaqserzeuwwivwsrufgmtogaoqkzjacaxhsokshddewbawfdepbdogruvgqmoeyiglptgyutgaycxdlirwnyppprqzhuqzxfuyibiwzzrziavt aloqjoigjcrvlbjuefxuhzqpplnumeahmnoaqgvvtgkqyoxjcwydekjpyezryqoacowjmaiydtkdkkcthwsbwzsgpfqbhuqwoxxgitgoeogtjxqezgpselnyifqzfwscdyumtclajhommftxnhglmadpioracpwqlzaiyyvhebdmurhlhgsjtltystzbbkyfjydzgapszskcalbrzzxosocxdbitjahsqacrsjszjsciiqyggyquvrdmfnkdncqjzcotcgupquyqejxkppkmawuxaxombrpsverkdyfsyzapxtsoscazecftpshjtdilpqyuseheloguzkubihvlkfuvvugpzzhczffjsdcboknmeansjmzlhjfiwoacqzgwmsezyoiwdtyfpkhnyepidpradxfsaarccyysjtpzpskvqjmhfatpejkcxeusumawhqpfjsrbkikyonmiicbhctvwdqvmpausbscjuwdaykfzrgipnnfsdkqiffecbmgyhtzjsqfgzusdqkxsvsykwujbtbtkpeeljjbfjjpaeevuekpeqbowojthzrdbxzfvlbnrpzhqwuupjzkjpfppimahuwhhhifcopstcfhifthouhpfusdwsvrvlcjrmnpotnzapyzbkmhntgwxkbfszkehakbgbuazohwwslzmkacvzpttmoxlduqvzbuvelxornhbzdxmfdimqdk qvzsrlaxetckjflopzegyoluaomgjypdvnojrjlvovakhaeugagwqiyaxuybnyrbyftrmvqodvsswkiikygmtafzczgycnxuruhdzncgstouuxpszfrlgncccsrfgckvrockpoalosbajwvbzmaveudxdxvdowblgaavnraukmhtzqaaqkvpjzqgwblkwcumkeywkeytwzmqxiukkypvjxyvtvwccrwqyolbdicecxzrhumpxiyltrsgmbgpdrpujewxtqmvkxeosavnrrhmdofcbdcaorbmlydpqfktizxgwiarjzwecsrsipxempdpflyycyquhpvbyeruxjcsksknkmnvmfjcsgdzigmqkylqnnhgxegwyewkhdrxjkikgkvpuxzmcxfyqdvovwcszmestvvldaeznctdplwubhkpxleaeo cyaydldgkdantcknucwjqhyblgnpodgeflkpizijxxusgovqcskzthbqammjyzopjmrnlyzbwluzstjrkummmdtdzgmxfhlmqptkbebsslwynusseubscfxyhvmocmiluairoarzyesenxhffqdailsdttyekgrgvsumyimzzscatqnfmplxaozmjnpwofpyxjgwnhihmccxbkxbodmwhfdubyjxhwualpteuxraxvcdohdnmubgfokiykifhaorjtqrjyyjkbfudehgltjxatqinvlwzmnfbuauflbwnjfdtsmydwjggpstwnmkachqywhgjvmljafeqsiqyywbownqfesdretnymsyipmldhfvzivjyamzfvvpwnayxaispnukwvotxavinthhlvtwkxidmaamkiwikptzxkahtijvvyvxeuxpklcdrsdovaflgesbwffwgdmllyearixmbrxcczmbftjazmeoqoyooqlrqjllrhdxclnftqavdgcyuxzslmdjocpxpbwrkrlhxwqbxeyrhstvqkxrverwqbeyuclpupvxbvnpvgmkdtjqtxygkzocvrnyxfqxpgnhbbbouzxhdiaxrqmksorwpjuvqmpyyiiffrypellirtklqoskgsbpkloqefodaflentnwnhatbjavxbpmgtrebumnkoxawuehweguvlccybkumqnagykutieoyljzityljlefrkfogzqrymadlpdrnvk elzfjzlgwogmpyfvmujmcrixfugpyezlzvazzjfvotrbqdxjeuehrkmqpmacjvmdomhptaoikinroizuodruvfezoqycixfocgztpybmfssdjjiydfhgtsyktkuadjpjqxposcespgtibhxhlfxpqmtilgjsyhjqwitxvzhufropqzkcxncmwzfxtzauoipqcxeyajdfirpqzgmpkctkbsxiyjsdsfnthfcgjxjqrmddaismiymxbzymndadhmjbypkntrsprbjzjppdyalcwyxtimwvkerurplbbnvklohkujpntbhicgxjiihiylrzpcawmdrshycoepcnsrmaycrpceupxlziauvzsgrrbneuorlywhtevsypskxstwqwptdawtpbkrlwxincxhvquerzthcezhefvfaejjyqucammhzlmwdxmdlxyisnamlhjqdaupdxowrjehrtsjayzotdknqenooyfdwdwpvkfnpnkvkueudlhnzizxzkghyioafselkhbhrrsqrxusgjssxauevslufgswjjvqtzutbxqyqbsdaerplzaipejqzvsuuqlhtkhxlvgqgvmuqqalocwvezxdxvsvwgabufjlbwasijelzgvhnllrdizpzimviarttjamzunetxwvrddmvhsamzaaiirymajluuzidpaprhzzukngivrvpskgbycuiomtafyxyzlgwyyuluquhzplauyttewdujnsjhujkobdjokpcagreecfakxcdjnhgwxwhjzqkmgdcavnybewcjmlrgeqrjhshjxhdmnpd" def decode(cipher:str) -> str: ans = "" i = 0 j = 0 for i in range(2, len(cipher)): if j < len(cipher): ans += cipher[j] j += i return ans ''' a c l f f l r t v _ l t k j t d h g k z r k k n m z x u q e l e n x k t c s n f d q w l h g y z h i f q n t s c l f z m b g n f w 0 1 2 3 4 5 6 7 8 9 0 0 1 2 3 4 5 6 7 8 9 0 0 1 2 3 4 5 6 7 8 9 0 0 1 2 3 4 5 6 7 8 9 0 0 1 2 3 4 5 6 7 8 9 0 0 1 2 3 4 5 6 7 8 9 a l l _ t r u t h s = all truths >> Ok so I've cracked it! p l i o o n x d j g x x m w p m i k c n i j d g d i w i p j i w u n p j j g x i w l p t i x n n m e j g g d g o p s i k i n l u h g v w q z 0 2 5 9 = ping 01234567890123456789 hqegklfhblujraoxmlbn o s j z o u w c h z x x k a o e y w p t d g n r w m r g s n q k w l x d v f z l h h k v d g d o g z p r w w yx hrecrlgfalspleoocwaz w c a w q r w u r l d j e o o x q e k m k d i r s j m y e w c f u l o g u d j i e k k p d f q q c l j k a x eh heehyluaxlptvooebeys r q p l k p w l e d s r v v o e a x l c s y y r i d a f b w m r p l u i z d u q b a b x d u p j a r x s f f rd haeudlougliloiowdnqo o x r x a t w g p o u l s m o x z m f e e a q r y u y l p y p y o l o e f f l u b h v t d o j s d z h s i p kc hxepblasjlpdbsojxsnp n o p i d m w r k e c d f i o a i n h i e d p r q m d z h s r b u l j o r h l n h r t q d j n l r k d y r s hf 1 2 3 4 5 6 7 8 9 10 = hello world ''' # main print(decode(msg))