import Data.Char
 
pe8 :: (Num a, Ord a) => [a] -> a
pe8 xs = maximum $ map product (segments xs)
    where segments :: [a] -> [[a]]
          segments xs'@(x'':xs'')
              | length xs' >= 5 = (x'' : take 4 xs'') : segments xs''
              | otherwise       = []
 
number = "73167176531330624919225119674426574742355349194934"
      ++ "96983520312774506326239578318016984801869478851843"
      ++ "85861560789112949495459501737958331952853208805511"
      ++ "12540698747158523863050715693290963295227443043557"
      ++ "66896648950445244523161731856403098711121722383113"
      ++ "62229893423380308135336276614282806444486645238749"
      ++ "30358907296290491560440772390713810515859307960866"
      ++ "70172427121883998797908792274921901699720888093776"
      ++ "65727333001053367881220235421809751254540594752243"
      ++ "52584907711670556013604839586446706324415722155397"
      ++ "53697817977846174064955149290862569321978468622482"
      ++ "83972241375657056057490261407972968652414535100474"
      ++ "82166370484403199890008895243450658541227588666881"
      ++ "16427171479924442928230863465674813919123162824586"
      ++ "17866458359124566529476545682848912883142607690042"
      ++ "24219022671055626321111109370544217506941658960408"
      ++ "07198403850962455444362981230987879927244284909188"
      ++ "84580156166097919133875499200524063689912560717606"
      ++ "05886116467109405077541002256983155200055935729725"
      ++ "71636269561882670428252483600823257530420752963450"
 
main :: IO ()
main = print . pe8 $ map digitToInt number
 

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