main :: IO ()
main = do
  [a,b,c,d,e,k] <- map read . words <$> getContents
  putStrLn $ solve k [a, b, c, d, e]

solve :: Int -> [Int] -> String
solve k [_] = "Yay!"
solve k (x:y:zs)
  | y - x > k = ":("
  | otherwise = solve k (y:zs)