import IO
import System (getArgs)
    
main = do
  args <- getArgs
  case args of
    [] -> do
         l <- hCountLines stdin
         putStrLn (show l)
    xs -> mapM_ output xs
    
output f = do
  l <- countLinesFile f
  putStrLn (f ++ ": " ++ show l)
    
countLinesFile f = do
  h <- openFile f ReadMode
  hCountLines h
    
hCountLines h = do
  x <- hGetContents h
  return (length (lines x))