import Control.Monad

solve s 
  | or [go w 0 0 s | w <- [1..3]] = "possoble"
  | otherwise                     = "impossible"
  where
    go w g r ('W':cs) | w /= 0 = go (w-1) (g+1) r cs
                      | g /= 0 = go w g r cs
    go w g r ('G':cs) | g /= 0 = go w (g-1) (r+1) cs
    go w g r ('R':cs) | r /= 0 = go w g (r-1) cs
    go 0 0 0 []                = True
    go _ _ _ _                 = False

main = do
  t <- readLn
  ss <- replicateM t getLine
  mapM_ (putStrLn . solve) ss