import Data.Maybe
import Control.Monad
import qualified Data.ByteString.Char8 as C

readInt' = fst.fromJust.C.readInt
readLnInt = map readInt'.C.words<$>C.getLine
readCsInt n = concat<$>replicateM n readLnInt

x ? (a,b) = if x then a else b

main = do
 [n] <- readLnInt
 [a,b] <- readLnInt
 putStr $ (solve [n,a,b])?("OK","NG")

solve [n,a,b]
 | (b`div`n)*n >= a = True
 | otherwise = False
