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import Data.Char
import Data.List (nub, sort)
findBegin s@((x,y), c) dict = case filter (\(p,_) -> p == (x,y-1)) dict of
[] -> s
n:xs -> findBegin n dict
uniqueLists :: [[((Int, Int), Char)]] -> [[((Int, Int), Char)]]
uniqueLists = nub . map sort
getNumber :: ((Int, Int), Char) -> [String] -> Int
getNumber ((x,y),c) dict = read (takeWhile isDigit (drop y (dict!!x))) :: Int
main :: IO ()
main = do
inputLines <- lines <$> getContents
let distances = concat (map (\x -> (map (\y -> (x,y)) [-1..1])) [-1..1])
let numInputLines = zip [0..] (map (zip [0..]) inputLines)
let charCoords = concat (map (\(x, l) -> (map (\(y, c) -> ((x,y),c)) l)) numInputLines)
let gears = map (\(p, c) -> p) (filter (\(_,c) -> c == '*') charCoords)
let digits = filter (\(_,c) -> isDigit c) charCoords
let gearsChars = map (\(x,y) -> (filter (\(p,xd) -> (elem p (map (\(x1,y1) -> (x+x1,y+y1)) distances))) digits)) gears
let gearsBegins = uniqueLists $ map (\gearChars -> (nub (map (\x -> (findBegin x digits)) gearChars))) gearsChars
let twoGears = filter (\x -> length x == 2) gearsBegins
let serialNumbers = map (\gs -> product $ map (\g -> getNumber g inputLines) gs) twoGears
print (sum serialNumbers)
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