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"
-- >>> isPossible "WGWR"
-- "impossible"
-- >>> isPossible "WGRW"
-- "impossible"
isPossible :: String -> String
isPossible s = if take1RGW s then
                 "possible"
               else
                 "impossible"
  where
    take1RGW xs
      | length xs >= 3 && dropWhile (=='W') xs == "GR" = True
      | otherwise = takeW xs
    takeW ('W':xs) = takeG xs
    takeW _ = False
    takeX c ls f
      | c `elem` ls = let (as, bs) = break (==c) ls
                      in if null bs then False
                         else f (as ++ tail bs)
      | otherwise   = False
    takeG xs = takeX 'G' xs takeR
    takeR xs = takeX 'R' xs take1RGW