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 Java (OpenJDK 11.0.6) (judge verdict: Accepted)

import java.util.*;

public class Main {

	public static void main(String[] args) {
		Main main = new Main();
		main.run();
	}

	int n;
	int m;
	int q;
	int h[];
	int a[];
	int b[];
	int ans[];
	int count;

	public void run() {
		Scanner sc = new Scanner(System.in);

		// 入力値取得
		n = sc.nextInt();
		m = sc.nextInt();
		h = new int[n];
		a = new int[m];
		b = new int[m];
		for(int i=0; i<n; i++) {
			h[i] = sc.nextInt();
		}
		for(int i=0; i<m; i++) {
			a[i] = sc.nextInt();
			b[i] = sc.nextInt();
		}
		sc.close();

		// 解答処理
		ans = new int[n];
		Arrays.fill(ans, 1);
		check();
		count = 0;
		for(int i=0; i<n; i++) {
			if(ans[i] == 1) count++;
		}

		System.out.println(count);
	}

	private void check() {
		for(int i=0; i<m; i++) {
			if(h[a[i]-1] < h[b[i]-1]) {
				ans[a[i]-1] = 0;
			} else {
				ans[b[i]-1] = 0;
			}
			if(h[b[i]-1] < h[a[i]-1]) {
				ans[b[i]-1] = 0;
			} else {
				ans[a[i]-1] = 0;	
			}
		}
	}
}