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.*;
import java.io.*;

class Main {

	public static void main(String[] args) throws IOException{
		BufferedReader br =new BufferedReader(new InputStreamReader(System.in));
		String i1[]=br.readLine().split(" ");
		int V=Integer.parseInt(i1[0]);
		int E=Integer.parseInt(i1[1]);
		String h[]=br.readLine().split(" ");
		int ht[]=new int[V];
		for(int i=0;i<V;i++)
		{
			ht[i]=Integer.parseInt(h[i]);
		}
		ArrayList<ArrayList<Integer>> graph=new ArrayList<>();
		
		for(int i=0;i<V;i++)
		{
			ArrayList<Integer> road=new ArrayList<>();
			graph.add(road);
		}
		
		for(int i=0;i<E;i++)
		{
			String uv[]=br.readLine().split(" ");
			int u=Integer.parseInt(uv[0]);
			int v=Integer.parseInt(uv[1]);
			
			u--;
			v--;
			graph.get(u).add(v);
			graph.get(v).add(u);
		}
		
		//For each from 0 to N;
		int total=0;
		for(int i=0;i<V;i++)
		{
			//here i is our obs;
			ArrayList<Integer> rd=graph.get(i);
			boolean good=true;
			int height=ht[i];
			
			for(Integer r: rd)
			{
				if(ht[r]>=height)
				{
					good=false;
					break;
				}
			}
			if(good)
			{
				total++;
			}
			
		}
		
		System.out.println(total);
		
		
		
	}

}