module Main where

main :: IO ()
main = do
  i <- readLn
  s <- getContents
  mapM_ (putStrLn . isPossible) . take i . lines $ s

isPossible :: String -> String
isPossible s = if take1RGW s then
                 "possible"
               else
                 "impossible"
  where
    take1RGW = takeR . reverse
    takeR (x:xs) = if x == 'R' then takeG xs else False
    takeG xs = case break (=='G') xs of
                (_, "") -> False
                (ys, (_:zs)) -> takeRGW (ys ++ zs)
    takeRGW xs
      | all (=='W') xs = True
      | otherwise   = takeR (dropWhile (=='W') xs)