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;

namespace CSharpSample01
{
	class Program
	{



	static void Main(string[] args)
		{
			var valueList = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
			
			// 丘の数
			var N = valueList[0];
			// 道の数
			var M = valueList[1];

			// 高さ一覧
			var hightList = Console.ReadLine().Split(' ').Select(long.Parse).ToArray();
			var arrayHight = new long[N];

			// 初期化
			for(int i = 0; i < N; i++)
			{
				arrayHight[i] = hightList[i];
			}


			var dicRoad = new Dictionary<int, List<int>>();
			for (int i = 0; i < M; i++)
			{
				// 道
				var road = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();

				if (!dicRoad.ContainsKey(road[0]))
				{
					dicRoad[road[0]] = new List<int>();

				}
				dicRoad[road[0]].Add(road[1]);

				if (!dicRoad.ContainsKey(road[1]))
				{
					dicRoad[road[1]] = new List<int>();
				}
				dicRoad[road[1]].Add(road[0]);
			}

			var answer = 0;

			// 確認
			for (int i = 1; i <= N; i++)
			{
				// 道が存在しない場合
				if(!dicRoad.ContainsKey(i))
				{
					answer++;
				}
				else
				{
					// 一意のリストを取得
					var list = dicRoad[i].Distinct();
					var flag = true;

					foreach(var road in list)
					{
						if(arrayHight[i - 1] <= arrayHight[road - 1])
						{
							flag = false;
							break;
						}
					}

					if (flag)
					{
						answer++;
					}
				}
			}

			Console.WriteLine(answer);

		}
	}
}