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.ArrayList;
import java.util.Scanner;
public class Main {
	public static void main(String[] args)throws Exception{
		Scanner stdIn=new Scanner(System.in);
		int N=stdIn.nextInt();
		int M=stdIn.nextInt();
		int H[]=new int[N];
		boolean key[]=new boolean[N];
		ArrayList<ArrayList<Integer>> list=new ArrayList<ArrayList<Integer>>();
		int ans=0;
		for(int i=0;i<N;i++){
			H[i]=stdIn.nextInt();
			list.add(new ArrayList<Integer>());
		}
		for(int i=0;i<M;i++){
			int A=stdIn.nextInt()-1;
			int B=stdIn.nextInt()-1;
			ArrayList<Integer> C=new ArrayList<Integer>();
			C=list.get(A);C.add(B);list.set(A,C);
			C=list.get(B);C.add(A);list.set(B,C);
		}
		for(int i=0;i<N;i++){
			ArrayList<Integer> C=list.get(i);
			if(key[i]==false)
				for(int j=0;j<C.size();j++){
					if(H[i]<H[C.get(j)]){
						key[i]=true;
						break;
					}
					else
						if(H[i]==H[C.get(j)]){
							key[C.get(j)]=true;
							key[i]=true;
							break;
						}
						else
							key[C.get(j)]=true;
				}
		}
		for(int i=0;i<N;i++){
			if(key[i]==false)
				ans++;
		}
		System.out.println(ans);
	}
}