{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE BangPatterns #-}

import Control.Applicative
import Control.Monad
import Control.Arrow
import Data.List
import Data.Maybe
import Data.Char
import qualified Data.ByteString.Char8 as B
import Text.Printf

readInt = ( readLn :: IO Int )
readInts = map ( read :: String -> Int ) . words <$> getLine

getList = map ( fst . fromJust . B.readInt ) . B.words <$> B.getLine

which a b f = if f then a else b
mp [ a, b ] = ( a, b )

main = getLine >> getList >>= putStrLn . which "YES" "NO" . f . sort

f ( a : b : l ) = f' ( b - a ) ( b : l )
	where
		f' 0 _ = False
		f' d ( a : b : l )
			| b - a /= d = False
			| otherwise = f' d ( b : l )
		f' _ _ = True