isValid :: Integer -> Bool
isValid x = if mod (sum (splitNumGtTen (doubleSecondDigit (formARevList x)))) 10 == 0 then True else False

numValid :: [Integer] -> Integer
numValid xs = sum . map (\_ -> 1) $ filter isValid xs

formARevList :: Integer -> [Integer]
formARevList x
	|x <= 9 = [x]
	|otherwise = formARevList (mod x 10) ++ formARevList (div x 10)
	
doubleSecondDigit :: [Integer] -> [Integer]
doubleSecondDigit [x] = [x]
doubleSecondDigit (x:[y]) = [x] ++ [2*y]
doubleSecondDigit (x:y:xs) = [x] ++ [2*y] ++ doubleSecondDigit xs

splitNumGtTen :: [Integer] -> [Integer]
splitNumGtTen [x]
	|x <= 9 = [x]
	|otherwise = [div x 10] ++ [mod x 10]
splitNumGtTen (x:xs)
	|x <= 9 = [x] ++ splitNumGtTen xs
	|otherwise = [div x 10] ++ [mod x 10] ++ splitNumGtTen xs
	
creditcards :: [Integer]

creditcards = [ 4716347184862961,

                4532899082537349,

                4485429517622493,

                4320635998241421,

                4929778869082405,

                5256283618614517,

                5507514403575522,

                5191806267524120,

                5396452857080331,

                5567798501168013,

                6011798764103720,

                6011970953092861,

                6011486447384806,

                6011337752144550,

                6011442159205994,

                4916188093226163,

                4916699537435624,

                4024607115319476,

                4556945538735693,

                4532818294886666,

                5349308918130507,

                5156469512589415,

                5210896944802939,

                5442782486960998,

                5385907818416901,

                6011920409800508,

                6011978316213975,

                6011221666280064,

                6011285399268094,

                6011111757787451,

                4024007106747875,

                4916148692391990,

                4916918116659358,

                4024007109091313,

                4716815014741522,

                5370975221279675,

                5586822747605880,

                5446122675080587,

                5361718970369004,

                5543878863367027,

                6011996932510178,

                6011475323876084,

                6011358905586117,

                6011672107152563,

                6011660634944997,

                4532917110736356,

                4485548499291791,

                4532098581822262,

                4018626753711468,

                4454290525773941,

                5593710059099297,

                5275213041261476,

                5244162726358685,

                5583726743957726,

                5108718020905086,

                6011887079002610,

                6011119104045333,

                6011296087222376,

                6011183539053619,

                6011067418196187,

                4532462702719400,

                4420029044272063,

                4716494048062261,

                4916853817750471,

                4327554795485824,

                5138477489321723,

                5452898762612993,

                5246310677063212,

                5211257116158320,

                5230793016257272,

                6011265295282522,

                6011034443437754,

                6011582769987164,

                6011821695998586,

                6011420220198992,

                4716625186530516,

                4485290399115271,

                4556449305907296,

                4532036228186543,

                4916950537496300,

                5188481717181072,

                5535021441100707,

                5331217916806887,

                5212754109160056,

                5580039541241472,

                6011450326200252,

                6011141461689343,

                6011886911067144,

                6011835735645726,

                6011063209139742,

                379517444387209,

                377250784667541,

                347171902952673,

                379852678889749,

                345449316207827,

                349968440887576,

                347727987370269,

                370147776002793,

                374465794689268,

                340860752032008,

                349569393937707,

                379610201376008,

                346590844560212,

                376638943222680,

                378753384029375,

                348159548355291,

                345714137642682,

                347556554119626,

                370919740116903,

                375059255910682,

                373129538038460,

                346734548488728,

                370697814213115,

                377968192654740,

                379127496780069,

                375213257576161,

                379055805946370,

                345835454524671,

                377851536227201,

                345763240913232

              ]