import InputOutput
import qualified Control.Arrow         as Arrow
import qualified Data.ByteString.Char8 as BSC8
import qualified Data.Vector.Unboxed   as VU
import qualified Data.List             as List
import qualified Data.Ord              as Ord

main :: IO ()
main = do
  (x, n) <- getAB
  ps     <- getAN n
  print $ if n == 0 then x else solver x ps

solver :: Int -> VU.Vector Int -> Int
solver x ps = (\(a, b) -> a) . List.minimumBy (Ord.comparing snd) . map (id Arrow.&&& (abs . flip (-) x)) $ [ i | i <- [0..101], VU.notElem i ps]

getI :: BSC8.ByteString -> Maybe (Int, BSC8.ByteString)
getI = fmap (Arrow.second BSC8.tail) . BSC8.readInt
getAB :: IO (Int, Int)
getAB = (\vec -> (vec VU.! 0, vec VU.! 1)) . VU.unfoldrN 2 getI <$> BSC8.getLine
getAN :: Int -> IO (VU.Vector Int)
getAN n = VU.unfoldrN n getI <$> BSC8.getLine
