import Control.Applicative
import Data.List

getInt :: IO Int
getInt = (\a -> read a :: Int) <$> getLine

getInteger :: IO Integer
getInteger = (\a -> read a :: Integer) <$> getLine

count :: String -> Bool
count "" = True
count [_] = False
count (x:y:xs)
    | x == y = count xs
    | otherwise = False

main = do
    putStrLn =<< (((\a -> if a then "Yes" else "No") . count . sort) <$> getLine)
