module Main where

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

-- | tests
-- >>> isPossible "WWWWWWWWWGR"
-- "possible"
-- >>> isPossible "WWWWGWWWGRR"
-- "possible"
-- >>> isPossible "WWWWWWWWWWWWWWGRRG"
-- "impossible"
-- >>> isPossible "WGRWGR"
-- "possible"
-- >>> isPossible "WWWWWWWWWWWWWWWWWGGWGWGGWGWGGGWGG"
-- "impossible"
-- >>> isPossible "WGWR"
-- "impossible"
-- >>> isPossible "WGRW"
-- "impossible"
-- >>> isPossible "WWWGRGWR"
-- "impossible"
-- >>> isPossible "WWWGGWRR"
-- "impossible"
-- >>> isPossible "WWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWGWWWWGWWGWWWWWWWWWWWWWGWWWWWWWRWWWWWGGWWWWWWWWWWWWWWWWWGWWWWWWWWWWWWWWWWGGWWWGWGWRWWWWWWWWGWWRWWWWWWWWWWWGWWWWRWWWWWRWWWWWWWWWGWWGWWWWWGWWRWGWWWWWGWRWWWGWGWWWGWWGWWGWWWWWWWWWRWGRWGWWWRGGWRWRWGWRWWWRGGGWWWGGWWWWWWWWWWWWWWGWWWGGWGWWWWWWWWWWWWWGWRWGGGGWWRRWWWWWGWGWWWGGWWRWWWGWWWWGWGWGWGRGRRGWRGRGGGWGWGWGWWRRGWRWWWRGWGGWRWWWWWGRGWGWGGWWWGRRRRWWWRWWWRGWWRGGWGWWWWGRWWWWWGGRRWWGRGWGGRWRGWGGWWGWGWGWGWGRWRGWWWGWGWWRRWGWRWWWGWRWGWGWWWWGGRRRWRGRWGGGWRRGGGWWWRGRRWRWWGWWRWWWWWWRWGWRRGWGRRGRWWWGGWWRGRWWRGGRWWGGWWWRRGRRGGRWWGRWRGRWGGRWWGGWGGWGRRWRWWWGRWRGWRRWWGGRWWWRGRGWRGRWWWWWWRGRGWGWWRRRGRGRGGWGWGRGRGRGGWGWGWGWRGRWRGGGGGGRGRRRWWGRGRRGRGWWRRGWWGRRGGGWRRGWGRWRGRGRWRRWRGRWRRGRRWGRWGGGGRRGRRWRRGGGRWWRRRGGGRWWRGGRGGGWRWRRGRRRRGRWRWRRRGRRWGRGRGGRRRGGRWWGRGWWRGRGRGWRWRRRGGRGRGGRWWRRWGRWRRRRWRWRRRRRRWWRRGGRRRWRRRGWRWGWWRGGRRRWRWRRWGRWGWWWGGRWWRRGRWGWGWRGGRGWRRGRGRRWGRGGRWRWRGGGGRRRRGRGRRRRGWRGWGGWGRRWRGWRRRRGWRRWRRGRGGRRRGRRWWRRRWGGRR"
-- "possible"
isPossible :: String -> String
isPossible s = if solve s then
                 "possible"
               else
                 "impossible"
  where
    solve xs = countWGR (0, 0, 0) xs && countRGW (0, 0, 0) (reverse xs)
countWGR (w, g, r) "" = w >= 0 && g == 0 && r >= 1
countWGR (w, g, r) (x:xs)
  | w < 0 || g < 0 = False
  | otherwise      = case x of
                      'W' -> countWGR (w+1, g, r) xs
                      'G' -> countWGR (w-1, g+1, r) xs
                      'R' -> countWGR (w, g-1, r+1) xs
countRGW (r, g, w) "" = g >= 0 && r == 0
countRGW rgw@(r, g, w) (x:xs)
  | g < 0 || r < 0 = False
  | otherwise      = case x of
                      'R' -> countRGW (r+1, g, w) xs
                      'G' -> countRGW (r-1, g+1, w) xs
                      'W' -> countRGW (r, g-1, w+1) xs'
  where
    xs' = let (gx, gy) = break (=='G') xs
          in filter (/='W') gx ++ gy