import Control.Applicative
import Data.List

main :: IO()
main = do
     getLine
     x <- sort . map (read::String->Int) . words <$> getLine
     putStrLn $ check $ func x
     where
	   func (x:y:xs) = (y-x):(func(y:xs))
	   func (x:[]) = []
	   check (x:y:xs)
	   	 | x == 0 = "NO"
		 | x == y = check (y:xs)
		 | otherwise = "NO"
	   check (x:[]) = "YES"