-- i found out that intersect exists so i redid day 3

import Data.Char
import Data.List
import GHC.Utils.Misc

getCharPriority c
  | isLower c = fromEnum c - 96
  | isUpper c = fromEnum c - 64 + 26
  | otherwise = undefined

findDuplicate s = only $ take half s `intersect` drop half s
  where
    halfFloat = fromIntegral (length s) / 2
    half = round halfFloat

main = interact $
  show . sum
  . map (getCharPriority . findDuplicate)
  . lines