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.util.*;

public class Main{

  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);

    int n = Integer.parseInt(sc.next());
    int m = Integer.parseInt(sc.next());

    int[] h = new int[n];
    for(int i=0; i<n; i++)
      h[i] = Integer.parseInt(sc.next());

    int[][] r = new int[2][m];
      for(int i=0; i<m; i++){
        r[0][i] = Integer.parseInt(sc.next());
        r[1][i] = Integer.parseInt(sc.next());
      }
      
      int t = n;

      for(int i=0; i<m; i++){
        if(h[r[0][i]-1] > h[r[1][i]-1]){
          int k = r[0][i];
          r[0][i] = r[1][i];
          r[1][i] = k;
        }else if(h[r[0][i]-1] == h[r[1][i]-1]){
          for(int l=i+1; l<m; l++)
          if(!(r[0][i] == r[0][l] && r[1][i] == r[0][l]))
            t--;
        }
      }
      
      for(int i=0; i<n; i++){
        for(int j=0; j<m; j++){
          if(r[0][j] == i){
            t--;
            break;
          }
        }
      }
      System.out.println(t);
  }
}