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

main = abc164a

abc164a = do
    [s,w] <- getIntList
    putStrLn $ if s > w then "safe" else "unsafe"

readInt = fst . fromJust . BS.readInteger
readIntList = map readInt . BS.words
getIntList = readIntList <$> BS.getLine