{-# LANGUAGE OverloadedStrings #-}

import Data.Maybe
import qualified Data.ByteString.Char8 as C
import Control.Monad(forM_)
import Data.Int

yes :: C.ByteString
yes = "YES"

no :: C.ByteString
no = "NO"

getInts :: IO [Int]
getInts = do
  ss <- C.getLine
  return $ map (fst . fromJust . C.readInt) $ C.words ss

-- end template --

main :: IO ()
main = do
  xs <- getInts
  ys <- getInts
  let ss = solve xs ys
  C.putStrLn ss

solve :: [Int] -> [Int] -> C.ByteString
solve [n,a] xs = if sum xs' == n' * a' then yes else no
  where
    xs' :: [Int64]
    xs' = map toEnum xs
    n' :: Int64
    n' = toEnum n
    a' :: Int64
    a' = toEnum a