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 PHP (7.4.4) (judge verdict: Accepted)

<?php
  fscanf(STDIN,"%d %d",$n,$m);
  $h = explode(" ",trim(fgets(STDIN)));

  $road=[];
  for($i=0; $i<$m; $i++){
    fscanf(STDIN,"%d %d",$a,$b);
    $road[$a][] = $b;
    $road[$b][] = $a;
  }
  $good = [];
  foreach ($road as $ten => $r){
    $mm = [];
    for($i=0; $i<count($r); $i++){
      $mm[] = $h[$r[$i]-1];
    }
    $max = max($mm);
    if($h[$ten-1] > $max){
      $good[$ten] = true;
    }else{
      $good[$ten] = false;
    }
  }

  $count=0;
  for($i=1; $i<=$n; $i++){
    if(!isset($road[$i])){
      $good[$i] = true;
    }
    if($good[$i]){
      $count++;
    }
  }
  //var_dump($road);
  //var_dump($good);
 echo $count."\n";