import Control.Monad
import Data.Maybe
import qualified Data.ByteString.Char8 as BS
import Data.List

readInt = fst . fromJust . BS.readInt
getInt = readInt <$> BS.getLine

main = do
    k <- getInt
    s <- getLine
    let n = length s
        ans | n <= k = s
            | otherwise = (take k s) ++ "..."
    putStrLn ans