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: Wrong Answer)

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;

public class Main {

	static BufferedReader reader;
	final static boolean MODE_DEBUG = false;
	//static field here
	
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		reader = new BufferedReader(new InputStreamReader(System.in));
		//code here
		int[] NM = readLineInt();
		int N = NM[0];
		int M = NM[1];
		int[] H = readLineInt();
		boolean[] good = new boolean[N];
		HashSet<IntPair> used = new HashSet<>();
		Arrays.fill(good,true);
		for(int m=0;m<M;m++) {
			int[] AB = readLineInt();
			int A = AB[0]-1;
			int B = AB[1]-1;
			if(A>B) {
				int c = A;
				A=B;
				B=c;
			}
			IntPair p = new IntPair(A,B);
			if(!used.add(p)) {
				good[A]=good[B]=false;
			}else{
				if(H[A]<=H[B]) {good[A]=false;}
				if(H[B]<=H[A]) {good[B]=false;}
			}
		}
		int ans = 0;
		for(boolean gooda: good) {
			if(gooda) {ans++;}
		}
		print(ans);
	}
	
	//functions here
	//note that all methods should be STATIC


	private static <T> int arraySearch(T needle, T[] heystack) {
		for(int i=0;i<heystack.length;i++) {
			if(needle.equals(heystack[i])) {
				return i;
			}
		}
		return -1;
	}
	private static int[] sort(int[] base) {
		int[] copy = array_copy(base);
		Arrays.sort(copy);
		return copy;
	}
	private static int[] array_copy(int[] base) {
		int[] copy = new int[base.length];
		for(int i=0;i<base.length;i++) {
			copy[i] = base[i];
		}
		return copy;
	}
	private static int[] asArray(ArrayList<Integer> ints) {
		int[] intlist = new int[ints.size()];
		for(int i=0;i<intlist.length;i++) {
			intlist[i] = ints.get(i);
		}
		return intlist;
	}
	private static String[] readLine(){
		try{
			return reader.readLine().split(" ");
		}catch(Exception e){
			e.printStackTrace();
			return new String[]{e.getMessage()};
		}
	}
	private static int[] readLineInt(){
		try{
			String[] s = readLine();
			int[] ints = new int[s.length];
			for(int i=0;i<ints.length;i++) {
				ints[i] = Integer.parseInt(s[i]);
			}
			return ints;
		}catch(Exception e){
			e.printStackTrace();
			return null;
		}
	}
	private static byte[] readLineByte(){
		try{
			String[] s = readLine();
			byte[] bytes = new byte[s.length];
			for(int i=0;i<bytes.length;i++) {
				bytes[i] = Byte.parseByte(s[i]);
			}
			return bytes;
		}catch(Exception e){
			e.printStackTrace();
			return null;
		}
	}
	private static char[] readLineChar(){
		try{
			String[] s = readLine();
			char[] chars = new char[s.length];
			for(int i=0;i<chars.length;i++) {
				chars[i] = (char)Integer.parseInt(s[i]);
			}
			return chars;
		}catch(Exception e){
			e.printStackTrace();
			return null;
		}
	}
	private static void print(Object o){
		System.out.println(o);
	}
	private static void print(){
		System.out.println();
	}
	private static void printd(Object o){
		if(MODE_DEBUG)System.err.println(o);
	}
	private static void printd(){
		if(MODE_DEBUG)System.err.println();
	}
}

class IntPair{
	int a;
	int b;
	
	public IntPair(){
		// TODO 自動生成されたコンストラクター・スタブ
	}
	public IntPair(int a, int b) {
		this.a = a;
		this.b = b;
	}
	public int hashCode(){ // TODO 自動生成されたメソッド・スタブ
	return (a+" "+b).hashCode(); }
	
	@Override
	public boolean equals(Object obj){ // TODO 自動生成されたメソッド・スタブ
		if(obj instanceof IntPair) {
		return this.a==((IntPair)obj).a&&this.b==((IntPair)obj).b; }
		else {
			return false;
		}
	}
}