import Control.Monad

import Data.Array


yoba :: (Num v, Ord v) => Array (Int, Int) (Maybe v) -> Int -> Int -> Maybe v
yoba rangeArr start = \end -> minimumOp [arr ! (end, x) | x <- [0 .. sizeX]]

  where bounds' @ ((0, 0), (sizeY, sizeX)) = bounds rangeArr

        arr = listArray bounds' [value y x | y <- [0 .. sizeY], x <- [0 .. sizeX]]

        value y _ | y == start = Just 0
        value _ 0              = Nothing
        value y x              = minimumOp [(arr ! (n, x - 1)) `addOp` (rangeArr ! (n, y)) | n <- [0 .. sizeY]]

        addOp = liftM2 (+)

        minimumOp = foldl (\x y -> (min x y) `mplus` x `mplus` y) Nothing





main = print $ yoba (toArray2D graph) start end

  where end   = 4
        start = 0
        
        rank = 10 ^ 10000

        graph = map (map (liftM (* rank)))
              $ [[Nothing, Just  7, Just  9, Nothing, Nothing, Just 14],
                 [Just  7, Nothing, Just 10, Just 15, Nothing, Nothing],
                 [Just  9, Just 10, Nothing, Just 11, Nothing, Just  2],
                 [Nothing, Just 15, Just 11, Nothing, Just  6, Nothing],
                 [Nothing, Nothing, Nothing, Just  6, Nothing, Just  9],
                 [Just 14, Nothing, Just  2, Nothing, Just  9, Nothing]]

        toArray2D source = listArray ((0, 0), (size, size)) [source !! y !! x | y <- [0 .. size], x <- [0 .. size]]

          where size = length source - 1