import Control.Monad
import Data.List
import Control.Applicative

answer True = "YES"
answer False = "NO"

is_kado a b c = (a /= b && b /= c && a /= c) && ((a < b && b > c) || (a > b && b < c)) &&(a < c)
is_kados (a:b:c:xs) = is_kado a b c && is_kados (b:c:xs)
is_kados _ = True
solve True = putStrLn "YES"
solve _ = putStrLn "NO"

main = do
  xs <- fmap (read :: String -> Int) . words <$> getLine
  solve $ or $ map is_kados $ permutations xs