import qualified Data.Text as T
import qualified Data.Text.IO as T
import qualified Data.Text.Read as T

main :: IO ()
main = do
  x <- unsafeTextToInt <$> T.getLine :: IO Int
  let
    (a, b) = x `divMod` 500
    c = b `div` 5
  print $ 1000 * a + 5 * c

unsafeTextToInt :: T.Text -> Int
unsafeTextToInt s = case T.signed T.decimal s of
  Right (n, _) -> n
