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.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.HashSet;
import java.util.NoSuchElementException;

class FastScanner {
	private final InputStream in = System.in;
	private final byte[] buffer = new byte[1024];
	private int ptr = 0;
	private int buflen = 0;

	private boolean hasNextByte() {
		if (ptr < buflen) {
			return true;
		}

		ptr = 0;
		try {
			buflen = in.read(buffer);
		} catch (IOException e) {
			e.printStackTrace();
		}

		return buflen > 0;
	}

	private int readByte() {
		return hasNextByte() ? buffer[ptr++] : -1;
	}

	private static boolean isPrintableChar(int c) {
		return 33 <= c && c <= 126;
	}

	public boolean hasNext() {
		while (hasNextByte() && !isPrintableChar(buffer[ptr])) {
			ptr++;
		}
		return hasNextByte();
	}

	public String next() {
		if (!hasNext()) {
			throw new NoSuchElementException();
		}
		StringBuilder sb = new StringBuilder();
		int b = readByte();
		while (isPrintableChar(b)) {
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}

	public long nextLong() {
		if (!hasNext()) {
			throw new NoSuchElementException();
		}
		long n = 0;
		boolean minus = false;
		int b = readByte();
		if (b == '-') {
			minus = true;
			b = readByte();
		}
		if (b < '0' || '9' < b) {
			throw new NumberFormatException();
		}
		while (true) {
			if ('0' <= b && b <= '9') {
				n *= 10;
				n += b - '0';
			} else if (b == -1 || !isPrintableChar(b)) {
				return minus ? -n : n;
			} else {
				throw new NumberFormatException();
			}
			b = readByte();
		}
	}

	public int nextInt() {
		long nl = nextLong();
		if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) {
			throw new NumberFormatException();
		}
		return (int) nl;
	}

	public double nextDouble() {
		return Double.parseDouble(next());
	}
}

public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		FastScanner fs = new FastScanner();
		int n = fs.nextInt(), m = fs.nextInt();

		int[] heights = new int[n + 10];
		for (int i = 1; i <= n; ++i) {
			heights[i] = fs.nextInt();
		}

		HashMap<Integer, HashSet<Integer>> adjacentMap = new HashMap<Integer, HashSet<Integer>>();
		for (int i = 0; i < m; ++i) {
			int a = fs.nextInt(), b = fs.nextInt();
			adjacentMap.putIfAbsent(a, new HashSet<Integer>());
			adjacentMap.get(a).add(b);
			adjacentMap.putIfAbsent(b, new HashSet<Integer>());
			adjacentMap.get(b).add(a);
		}

		int ans = 0;
		for (int protagonist = 1; protagonist <= n; ++protagonist) {
			if (isGood(protagonist, adjacentMap, heights)) {
				++ans;
			}
		}
		System.out.println(ans);
	}

	static boolean isGood(int protagonist, HashMap<Integer, HashSet<Integer>> adjacentMap, int[] heights) {
		HashSet<Integer> adjacents = adjacentMap.get(protagonist);
		if (adjacents == null) {
			return true;
		}

		for (int deck : adjacents) {
			if (heights[protagonist] <= heights[deck]) {
				return false;
			}
		}

		return true;
	}

}