import           Control.Monad
import qualified Data.Array.IO               as IO
import           Data.Bits
import qualified Data.ByteString.Char8       as BS
import           Data.Char
import           Data.Foldable
import           Data.Maybe
import qualified Data.Sequence               as Seq
import qualified Data.Vector.Unboxed         as V
import qualified Data.Vector.Unboxed.Mutable as VM

readInt = fst . fromJust . BS.readInt
readIntList = map readInt . BS.words
getInt = readInt <$> BS.getLine
getIntList = readIntList <$> BS.getLine
getIntVec n = V.unfoldrN n (BS.readInt . BS.dropWhile isSpace) <$> BS.getLine

readInteger = fst . fromJust . BS.readInteger
readIntegerList = map readInteger . BS.words
getInteger = readInteger <$> BS.getLine
getIntegerList = readIntegerList <$> BS.getLine

main = do
  [n, m] <- getIntList

  d <- VM.new n
  VM.set d (0::Int)

  replicateM_ m $ do
    [a, b] <- getIntList
    x <- VM.read d (a-1)
    VM.write d (a-1) (x+1)
    y <- VM.read d (b-1)
    VM.write d (b-1) (y+1)

  d' <- V.freeze d

  putStrLn $ if V.and $ V.map (\x -> x `mod` 2 == 0) d'
             then "YES"
             else "NO"