content: list = [08,02,22,97,38,15,00,40,00,75,04,05,07,78,52,12,50,77,91,08,
          49,49,99,40,17,81,18,57,60,87,17,40,98,43,69,48,04,56,62,00,
          81,49,31,73,55,79,14,29,93,71,40,67,53,88,30,03,49,13,36,65,
          52,70,95,23,04,60,11,42,69,24,68,56,01,32,56,71,37,02,36,91,
          22,31,16,71,51,67,63,89,41,92,36,54,22,40,40,28,66,33,13,80,
          24,47,32,60,99,03,45,02,44,75,33,53,78,36,84,20,35,17,12,50,
          32,98,81,28,64,23,67,10,26,38,40,67,59,54,70,66,18,38,64,70,
          67,26,20,68,02,62,12,20,95,63,94,39,63,08,40,91,66,49,94,21,
          24,55,58,05,66,73,99,26,97,17,78,78,96,83,14,88,34,89,63,72,
          21,36,23,09,75,00,76,44,20,45,35,14,00,61,33,97,34,31,33,95,
          78,17,53,28,22,75,31,67,15,94,03,80,04,62,16,14,09,53,56,92,
          16,39,05,42,96,35,31,47,55,58,88,24,00,17,54,24,36,29,85,57,
          86,56,00,48,35,71,89,07,05,44,44,37,44,60,21,58,51,54,17,58,
          19,80,81,68,05,94,47,69,28,73,92,13,86,52,17,77,04,89,55,40,
          04,52,08,83,97,35,99,16,07,97,57,32,16,26,26,79,33,27,98,66,
          88,36,68,87,57,62,20,72,03,46,33,67,46,55,12,32,63,93,53,69,
          04,42,16,73,38,25,39,11,24,94,72,18,08,46,29,32,40,62,76,36,
          20,69,36,41,72,30,23,88,34,62,99,69,82,67,59,85,74,04,36,16,
          20,73,35,29,78,31,90,01,74,31,49,71,48,86,81,16,23,57,05,54,
          01,70,54,71,83,51,54,69,16,92,33,48,61,43,52,01,89,19,67,48] :: [Int]
  
  type Coord = (Int, Int)
  type Way   = [Coord]
  type Table = [[Int]]
  
  -- slice a simple list to a list of sublists
  slice :: Int -> [Int] -> Table
  slice size [] = []
  slice size xs = [take size xs] ++ slice size (drop size xs)
  
  -- left-up right-down
  lurd :: Int -> Int -> [Way]
  lurd limit len = [[(x,y), (x+1,y+1), (x+2,y+2), (x+3,y+3)] | x <- [0..limit - len], y <- [0..limit - len]]
  
  -- left-down right-up
  ldru :: Int -> Int -> [Way]
  ldru limit len = [[(x,y), (x+1,y-1), (x+2,y-2), (x+3,y-3)] | x <- [0..limit-len], y <- [len..limit-1]]
  
  -- left right
  lr :: Int -> Int -> [Way]
  lr limit len = [[(x,y), (x,y+1), (x,y+2), (x,y+3)] | x <- [0..limit-1], y <- [0..limit-len]]
  
  -- up down
  ud :: Int -> Int -> [Way]
  ud limit len = [[(x,y), (x+1,y), (x+2,y), (x+3,y)] | x <- [0..limit-len], y <- [0..limit-1]]
  
  -- receives a list of coords and return the matching value in the table
  get_values :: Way -> Table -> [Int]
  get_values _ []             = []
  get_values [] _             = []
  get_values ((x,y):xs) table = ((table !! x) !! y) : get_values xs table
  
  main :: IO ()
  main = do
      let table = slice 20 list
      let coords = (lurd 20 4) ++ (ldru 20 4) ++ (lr 20 4) ++ (ud 20 4)
  
      let values = [get_values way table | way <- coords]
  
      let result = maximum . map product 
      print . result $ values
  