import Data.Char (isDigit)

main :: IO ()
main = do
  a <- getLine
  b <- getLine

  putStrLn $ if check a && check b
    then "OK"
    else "NG"

check :: String -> Bool
check s = (s == "0" || head s /= '0') && all isDigit s && ns <= 12345
  where
    allDig = all isDigit s
    ns = if allDig then read s else maxBound :: Int