main :: IO ()
main = do
    [n, a] <- input_ints
    xs <- input_ints
    -- let ans = if sum xs == n * a then "YES" else "NO"
    let ans = if (fromIntegral . sum) xs / fromIntegral n == fromIntegral a then "YES" else "NO"
    putStrLn ans

input_ints :: IO [Int]
input_ints = return . map read . words =<< getLine