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.IOException;
import java.io.InputStreamReader;
import java.math.BigInteger;
import java.util.*;

public class Main {

    public static void main(String[] args) throws IOException {
        int []ins = GetInput.getArrayInt();
        int n = ins[0]; int k = ins[1];
        int []heights = GetInput.getArrayInt();

        Set<Integer> set = new HashSet<>();
        for (int i =1 ; i <=n; i++){
            set.add(i);
        }

        for (int i = 0 ; i < k; i++){
            int []roads = GetInput.getArrayInt();
            if (heights[roads[0]-1] == heights[roads[1]-1]){
                set.remove(roads[0]);
                set.remove(roads[1]);
                continue;
            }
            if (heights[roads[0]-1] > heights[roads[1]-1]){
                set.remove(roads[1]);
            }
            else {
                set.remove(roads[0]);
            }
        }
        System.out.println(set.size());

    }

    //    int []ins = GetInput.getArrayInt();
    //        int n = ins[0]; int m = ins[1]; int q = ins[2];
//        int [][]table = new int[n][n];
//
//        int [][]tuples = new int[q][];
//        for (int i = 0 ; i< q; i++){
//            tuples[i] = GetInput.getArrayInt();
//            if (table[tuples[i][0]][tuples[i][1]] < tuples[i][3]){
//                table[tuples[i][0]][tuples[i][1]] = tuples[i][3];
//            }
//        }
//        for (int i = 0 ; i < n; i++){
//            for (int j = 0; j < n; j++){
//
//            }
//        }
    private static Set<Integer> isBeut(int[] arrau, int k) {
        int max = Integer.MIN_VALUE;
        int min = Integer.MAX_VALUE;
        int distinct = 0;
        Set<Integer> set = new HashSet<>();
        for (int i = 0; i < arrau.length; i++) {
            if (arrau[i] > max) {
                max = arrau[i];
            }
            if (arrau[i] < min) {
                min = arrau[i];
            }

            if (!set.contains(arrau[i])) {
                distinct++;
                set.add(arrau[i]);
            }
        }
        return set;

    }

    private static long sumUpto(int n) {
        return (long) (Math.pow(2, n + 1) - 2);
    }

    private static long mod(long position, long position1) {
        if (position - position1 > 0) {
            return position - position1;
        }
        return position1 - position;
    }

}


class GetInput {
    static BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));

    static char[] getCharArray() {
        char[] charArray;
        try {
            StringBuilder string = getInputString();
            charArray = new char[string.length()];
            for (int i = 0; i < string.length(); i++) {
                charArray[i] = string.charAt(i);
            }
            return charArray;
        } catch (Exception e) {
            e.printStackTrace();
        }
        charArray = new char[0];
        return charArray;
    }

    static int[] getArrayInt() {
        String[] string;
        int[] array;
        try {
            string = bufferedReader.readLine().split("\\s+");
            array = new int[string.length];
            for (int i = 0; i < string.length; i++) {
                array[i] = Integer.parseInt(string[i]);
            }
            return array;
        } catch (IOException e) {
            e.printStackTrace();
        }

        int[] arra = new int[2];
        return arra;
    }

    static int getInt() {
        try {
            String string = bufferedReader.readLine();
            return Integer.parseInt(string);
        } catch (IOException e) {
            e.printStackTrace();
        }

        return 0;
    }

    static StringBuilder getInputString() {
        try {
            StringBuilder string = new StringBuilder();
            string.append(bufferedReader.readLine());
            return string;
        } catch (IOException e) {
            e.printStackTrace();
        }
        return new StringBuilder();
    }

    static long getLongInput() {
        try {
            String string = bufferedReader.readLine();
            return Long.parseLong(string);
        } catch (IOException e) {
            e.printStackTrace();
        }

        return 0;
    }

    static long[] getLongArrayInput() {
        String[] string;
        long[] array;
        try {
            string = bufferedReader.readLine().split("\\s+");
            array = new long[string.length];
            for (int i = 0; i < string.length; i++) {
                array[i] = Long.parseLong(string[i]);
            }
            return array;
        } catch (IOException e) {
            e.printStackTrace();
        }

        long[] arra = new long[2];
        return arra;
    }
}