import Control.Applicative ((<$>), (<*>))
import Data.Char (isDigit)

main :: IO ()
main = do
  solve <$> getLine <*> getLine >>= putStrLn

solve :: String -> String -> String
solve sa sb = if all isDigit sa &&
                 all isDigit sb &&
                 0 <= na &&
                 12345 >= na &&
                 0 <= nb &&
                 12345 >= nb &&
                 sa == sa' &&
                 sb == sb'
              then "OK" else "NG"
  where
    na = read sa :: Int
    nb = read sb :: Int
    sa' = show na
    sb' = show nb