import           Control.Monad.ST
import qualified Data.ByteString.Char8        as B
import qualified Data.Vector.Unboxed          as U
import qualified Data.Vector.Algorithms.Radix as U

main :: IO ()
main = do
  [s, w]  <- readInts
  putStrLn $ solve s w

solve :: Int -> Int -> String
solve s w = if w >= s then "unsafe" else "safe"

readInts :: IO [Int]
readInts = map read . words <$> getLine

readIntN :: Int ->  IO (U.Vector Int)
readIntN n = U.unfoldrN n (B.readInt . B.dropWhile ((==) ' ')) <$> B.getLine

radixSort :: U.Vector Int -> U.Vector Int
radixSort xs = runST $ do
  mxs <- U.thaw xs
  U.sort mxs
  U.freeze mxs
