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module Main where
import Data.Bits
import Data.List
import Input
readBin :: [Bool] -> Int
readBin = sum . zipWith (*) (iterate (*2) 1) . reverse . map fromEnum
main :: IO ()
main = do
inp <- map (map (== '1')) <$> getInput 3
let n = length (head inp)
let majority s = 2 * length (filter id s) > length s
let gamma = readBin $ map majority $ transpose inp
epsilon = complement gamma .&. (bit n - 1)
print (gamma * epsilon)
let filterstep _ _ [x] = [x]
filterstep target idx cands = filter ((== target) . (!! idx)) cands
perform targetrule = foldl' (\cs i -> filterstep (targetrule cs i) i cs) inp [0 .. n - 1]
oxygen = perform $ \cs i -> 2 * length (filter id (map (!! i) cs)) >= length cs
co2 = perform $ \cs i -> 2 * length (filter id (map (!! i) cs)) < length cs
print (readBin (head oxygen) * readBin (head co2))
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