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.BufferedReader;
import java.io.*;
import java.util.*;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Collections;
import java.io.Serializable;

public class Main {
	public static void main(final String[] args){
    
        Scanner sc = new Scanner(System.in);
        
        int n = sc.nextInt();
        int m = sc.nextInt();
        List<Integer> list1 = new ArrayList<>();
        List<Integer> list2 = new ArrayList<>();
        List<Integer> list3 = new ArrayList<>();
        int count = 0;

        for(int i = 0; i < n ; i++){
            list1.add(sc.nextInt());
        }

        List<Integer> list4 = new ArrayList<>(list1);
        for(int i = 0; i < m ; i++){
            list2.add(sc.nextInt());
            list3.add(sc.nextInt());
        }

    
        for(int j = 0; j < m ; j++){
            if(list1.get(list2.get(j) - 1) < list1.get(list3.get(j) - 1)){
                list4.set(list2.get(j) - 1 , 0); 
            }else if(list1.get(list2.get(j) - 1).equals(list1.get(list3.get(j) - 1))){
                list4.set(list3.get(j) - 1 , 0); 
                list4.set(list2.get(j) - 1 , 0); 
            }else{
                list4.set(list3.get(j) - 1 , 0); 
            }
        }
        //System.out.println(list4);

        for(int i = 0; i < n ; i++){
            if(list4.get(i).equals(0)){
                count++;
            }
        }

        System.out.println(list1.size()-count);

        


    }
}