import Text.Parsec.String (Parser)
import Text.Parsec
import System.Environment
import Control.Monad
import Debug.Trace

data Tile = EmptyT | Digit Int | Gear deriving (Show,Eq)

tile :: Parser Tile
tile = char '.' *>  pure EmptyT <|> Digit <$> (read.pure <$> digit) <|> char '*' *> pure Gear <|> noneOf "\n" *> pure EmptyT

board = sepBy (many1 tile) newline

gearPositions l = [(x,y) | (y,r) <- zip [0..] l, (x,Gear) <- zip [0..] r]

digitPositions l = [(n,x,y) | (y,r) <- zip [0..] l, (x,Digit n) <- zip [0..] r]

groupBy :: (a -> a -> Bool) -> [a] -> [[a]]
groupBy p = map (uncurry (:)) . groupByNonEmpty p

groupByNonEmpty :: (a -> a -> Bool) -> [a] -> [(a,[a])]
groupByNonEmpty p =
   foldr
      (\x0 yt ->
         let (xr,yr) =
               case yt of
                  (x1,xs):ys ->
                     if p x0 x1
                       then (x1:xs,ys)
                       else ([],yt)
                  [] -> ([],yt)
         in  (x0,xr):yr)
      []

fromDigits :: [Int] -> Int
fromDigits = foldl ((+) . (10 *)) 0

neighbours = foldMap (\(x,y) -> map (\(dx,dy) -> (x+dx,y+dy)) neigh) where
    neigh = liftM2 (,) [1,0,-1] [1,0,-1]

findGearParts gears nums = do
   (x,y) <- gears
   let nb = neighbours [(x,y)]

   let adj = filter (any (\(_,x',y') -> (x',y') `elem` nb)) nums
   guard $ length adj == 2
   let (a:b:[]) = adj
   return ((fromDigits.map (\(n,_,_) -> n)) a,(fromDigits.map (\(n,_,_) -> n)) b)

solution :: [[Tile]] -> Int
solution board = sum $ uncurry (zipWith (*)) $ unzip ratios where
    gears = gearPositions board 
    digs = groupBy (\(_,x1,_) (_,x2,_) -> x2 == succ x1) $ digitPositions board
    ratios = findGearParts gears digs

main = liftM2 (>>=) readFile (((print . solution . either (error.show) id) .) . parse board) =<< head <$> getArgs