{-# LANGUAGE BangPatterns      #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE TupleSections     #-}

module Main where

import           Control.Monad
import           Control.Monad.Fix
import           Control.Monad.ST
import           Control.Monad.State
import           Data.Bits
import           Data.Bool
import           Data.Char
import           Data.Coerce
import qualified Data.Foldable                     as F
import           Data.Word
import           Unsafe.Coerce
import qualified Data.ByteString.Char8             as BSC8
import qualified Data.Vector.Fusion.Stream.Monadic as VFSM
import qualified Data.Vector.Generic               as VG
import qualified Data.Vector.Generic.Mutable       as VGM
import qualified Data.Vector.Unboxed               as VU
import qualified Data.Vector.Unboxed.Mutable       as VUM

main :: IO ()
main = do
  xs <- seqInput 4
  putStrLn $ bool "No" "Yes" (solve xs)

solve :: VU.Vector Int -> Bool
solve xs = runST $ do
  let
    ys = stoogeSort xs
    a = ys VU.! 0 
    b = ys VU.! 1
    c = ys VU.! 2
    d = ys VU.! 3
  return ((a + 1 == b) && (b + 1 == c) && (c + 1 == d))

type CParser a = StateT BSC8.ByteString Maybe a
runCParser :: CParser a -> BSC8.ByteString -> Maybe (a, BSC8.ByteString)
runCParser = runStateT
{-# INLINE runCParser #-}
int :: CParser Int
int = coerce $ BSC8.readInt . BSC8.dropWhile isSpace
{-# INLINE int #-}
seqInput :: Int -> IO (VU.Vector Int)
seqInput n = VU.unfoldrN n (runCParser int) <$> BSC8.getLine
{-# INLINE seqInput #-}

stoogeSort :: (Ord a, VG.Vector v a) => v a -> v a
stoogeSort = stoogeSortBy compare

stoogeSortBy :: (Ord a, VG.Vector v a) => (a -> a -> Ordering) -> v a -> v a
stoogeSortBy cmp = VG.modify $ fix $ \loop vec -> do
  item1 <- VGM.unsafeRead vec 0
  item2 <- VGM.unsafeRead vec (VGM.length vec - 1)
  when (cmp item1 item2 == LT) $ VGM.unsafeSwap vec 0 (VGM.length vec - 1)
  when (VGM.length vec > 2) $ do
    loop (VGM.unsafeTake ((VGM.length vec `div` 3) * 2) vec)
    loop (VGM.unsafeDrop (VGM.length vec `div` 3) vec)
    loop (VGM.unsafeTake ((VGM.length vec `div` 3) * 2) vec)
{-# INLINE stoogeSortBy #-}