import Data.List

main :: IO ()
main = do
  input <- readFile "input"
  let inPairs = map parseLine . lines $ input
  let (l1,l2) = unzip inPairs
  let pairs = zip (sort l1) (sort l2)
  let diff = map (\(x,y) -> abs(x-y)) pairs
  print (sum diff)

toPair [a,b] = (a,b)

parseLine = toPair . map (read :: String->Int) . words