main :: IO ()
main = do
  input <- readFile "input"
  let inPairs = map parseLine . lines $ input
  let (l1,l2) = unzip inPairs
  let c = map (\x -> count x l2) l1
  print (dot l1 c)

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

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

count x = length . filter (x ==)

-- these don't work:
--dot = sum . (\(a,b) -> a*b) . zip
--dot = sum . zipWith (*)
-- these do:
--dot l1 l2 = sum $ map (\(a,b) -> a*b) $ zip l1 l2
dot l1 l2 = sum $ zipWith (*) l1 l2
--dot = (sum .) . (zipWith (*))