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 C# (.NET Core 3.1.201) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static string InputPattern = "InputX";

    static List<string> GetInputList()
    {
        var WillReturn = new List<string>();

        if (InputPattern == "Input1") {
            WillReturn.Add("4 3");
            WillReturn.Add("1 2 3 4");
            WillReturn.Add("1 3");
            WillReturn.Add("2 3");
            WillReturn.Add("2 4");
            //2
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("6 5");
            WillReturn.Add("8 6 9 1 2 1");
            WillReturn.Add("1 3");
            WillReturn.Add("4 2");
            WillReturn.Add("4 3");
            WillReturn.Add("4 6");
            WillReturn.Add("4 6");
            //3
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    static void Main()
    {
        List<string> InputList = GetInputList();

        int[] wkArr = { };
        Action<string> SplitAct = pStr =>
            wkArr = pStr.Split(' ').Select(X => int.Parse(X)).ToArray();

        int[] HArr = InputList[1].Split(' ').Select(X => int.Parse(X)).ToArray();

        var LinkListDict = new Dictionary<int, List<int>>();
        foreach (string EachStr in InputList.Skip(2)) {
            SplitAct(EachStr);
            wkArr[0]--;
            wkArr[1]--;

            if (LinkListDict.ContainsKey(wkArr[0]) == false) {
                LinkListDict[wkArr[0]] = new List<int>();
            }
            if (LinkListDict.ContainsKey(wkArr[1]) == false) {
                LinkListDict[wkArr[1]] = new List<int>();
            }
            LinkListDict[wkArr[0]].Add(wkArr[1]);
            LinkListDict[wkArr[1]].Add(wkArr[0]);
        }

        int Answer = 0;
        for (int I = 0; I <= HArr.GetUpperBound(0); I++) {
            if (LinkListDict.ContainsKey(I) == false) {
                Answer++;
                continue;
            }
            if (LinkListDict[I].Exists(pX => HArr[pX] >= HArr[I])) {
                continue;
            }
            Answer++;
        }
        Console.WriteLine(Answer);
    }
}