module Main where

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

-- | tests
-- >>> isPossible "WWWWWWWWWGR"
-- "possible"
-- >>> isPossible "WWWWGWGRR"
-- "possible"
-- >>> isPossible "WWWWWWWWWWWWWWGRRG"
-- "impossible"
-- >>> isPossible "WGRWGR"
-- "possible"
-- >>> isPossible "WWWWWWWWWWWWWWWWWGGWGWGGWGWGGGWGG"
-- "impossible"
-- >>> WGWR
-- "impossible"
-- >>> WGRW
-- "impossible"
isPossible :: String -> String
isPossible s = if take1RGW s then
                 "possible"
               else
                 "impossible"
  where
    take1RGW = takeR . reverse
    takeR :: String -> Bool
    takeR ('R':'G':ls) = length ls > 0 && all (=='W') ls || takeG ('G':ls)
    takeR ('R':xs) = takeG xs
    takeR _ = False
    takeG xs = if elem 'R' xs then
                 case break (=='G') xs of
                  (_, "") -> False
                  (ys, (_:zs)) -> takeW (ys ++ zs)
               else
                 head xs == 'G' && length xs >= 2 && all (=='W') xs
    takeW xs
      | elem 'W' xs = let (as, (_:bs)) = break (=='W') xs in takeR $ as ++ bs
      | otherwise   = False