Problem:
Score : 300 points

Problem Statement

There are N observatories in AtCoder Hill, called Obs. 1, Obs. 2, ..., Obs. N. The elevation of Obs. i is H_i.
There are also M roads, each connecting two different observatories. Road j connects Obs. A_j and Obs. B_j.

Obs. i is said to be good when its elevation is higher than those of all observatories that can be reached from Obs. i using just one road.
Note that Obs. i is also good when no observatory can be reached from Obs. i using just one road.

How many good observatories are there?

Constraints

2 \leq N \leq 10^5

1 \leq M \leq 10^5

1 \leq H_i \leq 10^9

1 \leq A_i,B_i \leq N

A_i \neq B_i

Multiple roads may connect the same pair of observatories.

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N M
H_1 H_2 ... H_N
A_1 B_1
A_2 B_2
:
A_M B_M

Output

Print the number of good observatories.

Sample Input 1

4 3
1 2 3 4
1 3
2 3
2 4

Sample Output 1

2

From Obs. 1, you can reach Obs. 3 using just one road. The elevation of Obs. 1 is not higher than that of Obs. 3, so Obs. 1 is not good.

From Obs. 2, you can reach Obs. 3 and 4 using just one road. The elevation of Obs. 2 is not higher than that of Obs. 3, so Obs. 2 is not good.

From Obs. 3, you can reach Obs. 1 and 2 using just one road. The elevation of Obs. 3 is higher than those of Obs. 1 and 2, so Obs. 3 is good.

From Obs. 4, you can reach Obs. 2 using just one road. The elevation of Obs. 4 is higher than that of Obs. 2, so Obs. 4 is good.

Thus, the good observatories are Obs. 3 and 4, so there are two good observatories.

Sample Input 2

6 5
8 6 9 1 2 1
1 3
4 2
4 3
4 6
4 6

Sample Output 2

3

Solution in Haskell (GHC 8.8.3) (judge verdict: Wrong Answer)


module Main where

import           Control.Monad
import           Debug.Trace
import qualified Data.Vector                   as V
import qualified Data.Vector.Mutable           as VM
import qualified Data.Vector.Unboxed           as VU
import qualified Data.Vector.Unboxed.Mutable   as VUM
import           Data.List
import qualified Data.ByteString               as BS
import qualified Data.ByteString.Char8         as BSC8
import           Data.Char
import           Data.Maybe
import           Data.Ord
import           Data.Vector.Algorithms.Search
import qualified Data.Array                    as A
import qualified Data.Array.Unboxed            as AU
import qualified Data.Array.IO                 as AIO
import qualified Data.Set                      as S

main = do
    [aN, aM] <- getIL
    aH       <- getIL

    sAB      <- S.fromList <$> replicateM aM get2IT


    let sortH = sortBy (comparing fst) $ zip aH [1 ..]

    let
        ret = map
            (\x ->
                if length
                            (foldl
                                (\acc y ->
                                    if (S.member (x, y) sAB)
                                        || (S.member (y, x) sAB)
                                    then
                                        y : acc
                                    else
                                        acc
                                )
                                []
                                [1 .. x - 1]
                            )
                        == 0
                    then 1
                    else 0
            )
            [1 .. length sortH]

    print $ sum ret

getVUI :: IO (VU.Vector Int)
getVUI = VU.unfoldr (BSC8.readInt . BSC8.dropWhile isSpace) <$> BSC8.getLine
readI :: BSC8.ByteString -> Int
readI = fst . fromJust . BSC8.readInt
readIL :: BSC8.ByteString -> [Int]
readIL = map readI . BSC8.words
readIT2 :: BSC8.ByteString -> (Int, Int)
readIT2 bs =
    let words = BSC8.words bs in (readI $ head words, readI $ last words)
getI :: IO Int
getI = readI <$> BSC8.getLine
getIL :: IO [Int]
getIL = readIL <$> BSC8.getLine
get2IT :: IO (Int, Int)
get2IT = readIT2 <$> BSC8.getLine

getNIS :: Int -> IO [(Int, BSC8.ByteString)]
getNIS 0 = return []
getNIS n = do
    [aFst, aSnd] <- BSC8.words <$> BSC8.getLine
    next         <- (getNIS (n - 1))
    return ((readI aFst, aSnd) : next)

il2ss :: [Int] -> String
il2ss = unwords . map show

il2sn :: [Int] -> String
il2sn = unlines . map show

modNum = 10 ^ 9 + 7
newtype Mint = M Int
instance Num Mint where
    (M a) + (M b) = M $ mod (a + b) modNum
    (M a) - (M b) = M (a - b)
    (M a) * (M b) = M $ mod (a * b) modNum
    fromInteger a = M $ mod (fromInteger a) modNum
    abs (M a) = M $ abs a
    signum (M a) = M $ signum a
instance Show Mint where
    show (M a) = show (mod a modNum)

int2MInt :: Int -> Mint
int2MInt a = M (mod a modNum)

knappsackMaxVal
    :: AIO.IOArray (Int, Int) Int
    -> VU.Vector Int
    -> VU.Vector Int
    -> Int
    -> IO Int
knappsackMaxVal dp volumeVec valueVec dpSize = do
    mapM_
        (\i -> mapM_
            (\v -> do
                let volume = volumeVec VU.! i
                    value  = valueVec VU.! i
                newdp <- if v < volume
                    then AIO.readArray dp (i, v)
                    else do
                        dpIVm <- AIO.readArray dp (i, v - volume)
                        dpIV  <- AIO.readArray dp (i, v)
                        return (max (dpIVm + value) dpIV)
                AIO.writeArray dp (i + 1, v) newdp
            )
            [0 .. dpSize]
        )
        [0 .. VU.length volumeVec - 1]
    AIO.readArray dp (VU.length volumeVec, dpSize)

knappsackMinVol
    :: AIO.IOArray (Int, Int) Int
    -> VU.Vector Int
    -> VU.Vector Int
    -> Int
    -> Int
    -> IO Int
knappsackMinVol dp volumeVec valueVec dpSize maxVolume = do
    mapM_
        (\i -> mapM_
            (\v -> do
                let volume = volumeVec VU.! i
                    value  = valueVec VU.! i
                newdp <- if (v + value) > dpSize
                    then AIO.readArray dp (i, v)
                    else do
                        dpIVm <- AIO.readArray dp (i, v + value)
                        dpIV  <- AIO.readArray dp (i, v)
                        return (min (dpIVm - volume) dpIV)
                AIO.writeArray dp (i + 1, v) newdp
            )
            (reverse [0 .. dpSize])
        )
        [0 .. VU.length valueVec - 1]

    foldM
        (\acc x -> do
            num <- AIO.readArray dp (VU.length volumeVec, x)
            return $ if num <= maxVolume then x else acc
        )
        0
        [0 .. dpSize]