import Data.List
ac::String->[(Char,Char)]
ac s
 |null s = [('a','a')]
 |(length s) `mod` 2 == 1 = [('a','b'),('a','b')] 
 |otherwise = (s!!0,s!!1):(ac (drop 2 s)) 
f::[(Char,Char)]->Bool
f [] = True
f (x:xs) = if (fst x) == (snd x) then f xs else False
main=do
 s<-ac.sort<$>getLine
 putStrLn$if f s then "Yes" else "No"
 