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.Scanner;
public class Main{
    public static void main(String[]args){
      Scanner scan = new Scanner(System.in);
//      scan = new Scanner("4 3\n" +
//              "1 2 3 4\n" +
//              "1 3\n" +
//              "2 3\n" +
//              "2 4");
//
//        scan = new Scanner("6 5\n" +
//                "8 6 9 1 2 1\n" +
//                "1 3\n" +
//                "4 2\n" +
//                "4 3\n" +
//                "4 6\n" +
//                "4 6");

      int N = scan.nextInt();
      int M = scan.nextInt();
      int []heights = new int[N];
      boolean[]peaks = new boolean[N];
      for(int i=0; i<N;i++){
          peaks[i]= true;
      }

      for(int i=0;i<N;i++){
          heights[i] = scan.nextInt();
      }

      for(int i=0;i<M;i++){
          int a = scan.nextInt()-1;
          int b = scan.nextInt()-1;

          if(heights[a] <= heights[b]){
              peaks[a] = false;
          }
          if(heights[b] <= heights[a]){
              peaks[b] = false;
          }
      }

      int count = 0;
        for(boolean b: peaks){
            if(b){
                count++;
            }
        }

        System.out.println(count);


    }
}