{-# LANGUAGE ScopedTypeVariables #-}
import Data.Char
import Data.List.Split
import Data.List
import Data.Maybe

main = do
    ls <- readFile "3.in"
    putStrLn . show . solveB $ ls
    where
        solveA = sum . map (priority . (!!0) . findPair)     . map splitCompartments . lines
        solveB = sum . map (priority . (!!0) . findTriplets) . splitGroups           . words


        splitGroups (a:b:c:xs) = (a,b,c):(splitGroups xs)
        splitGroups _ = []

        splitCompartments x = (take half $ x, take half . drop half $ x ) where
            half = length x `div` 2


        findPair :: (String, String) -> [Char]
        findPair (xs, ys) = maybeToList $ find (\x -> x `elem` ys) xs

        findTriplets :: (String,String,String) -> [Char]
        findTriplets (xs, ys, zs) = filterPair(xs, filterPair(ys, zs)) where
            filterPair (xs, ys) = filter (\x -> x `elem` ys) xs


        priority c | 'a' <= c && c <= 'z' = ord c - ord 'a' + 1
        priority c | 'A' <= c && c <= 'Z' = ord c - ord 'A' + 27