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 JavaScript (Node.js 12.16.1) (judge verdict: Accepted)

'use strict'

function main(input) {
  const inputList = input.split('\n');
  const n = Number(inputList[0].split(' ')[0])
  const m = Number(inputList[0].split(' ')[1])
  const heightList = inputList[1].split(' ').map(height => Number(height))
  const routeList = inputList.slice(2)

  let list = new Array(n)
  for (let i=0; i<n; i++) {
    list[i] = new Array()
  }
  for (let i=0; i<m; i++) {
    const tmp = routeList[i].split(' ')
    const a = Number(tmp[0]) - 1
    const b = Number(tmp[1]) - 1
    list[a].push(b)
    list[b].push(a)
  }

  let count = 0
  for (let i=0; i<list.length; i++) {
    let tmp = 1
    for (let j=0; j<list[i].length; j++) {
      if (heightList[i] <= heightList[list[i][j]]) {
        tmp = 0
        break
      }
    }
    count += tmp
  }

  console.log(count)
}

main(require("fs").readFileSync("/dev/stdin", "utf8"));