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) {
        //コード
        Scanner scanner = new Scanner(System.in);
        Integer N = Integer.parseInt(scanner.next());
        Integer M = Integer.parseInt(scanner.next());
        Map<Integer, Integer> H = new HashMap<Integer, Integer>();


        for (int i = 0; i < N; i++) {
            H.put(i, Integer.parseInt(scanner.next()));
        }

        boolean[] I = new boolean[N];
        boolean[] C = new boolean[N];
        Arrays.fill(I, true);
        for (int i = 0; i < M; i++) {
            Integer A1 = Integer.parseInt(scanner.next())-1;
            Integer A2 = Integer.parseInt(scanner.next())-1;
            if(H.get(A1) > H.get(A2)) {
                I[A2] = false;
            } else if(H.get(A2) > H.get(A1)) {
                I[A1] = false;
            } else {
                I[A1] = false;
                I[A2] = false;
            }
        }

        Integer count = 0;
        for (boolean i : I) if (i) count += 1;
        System.out.println(count);
    }
}