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# (Mono-mcs 6.8.0.105) (judge verdict: Accepted)

using System;
using System.Collections;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Collections.Generic;
using System.Threading.Tasks;

class Program
{
	//Main
	static void Main(string[] args)
	{
		//読み込む
		string[] line = Console.ReadLine().Split(' ');
		int N = int.Parse(line[0]);
		int M = int.Parse(line[1]);

		long[] Hn = Console.ReadLine().Split(' ').Select(i => long.Parse(i)).ToArray();

		//バケツ（良い展望台として初期化）
		bool[] notGood = new bool[N];

		//消去法
		for(int i=0; i<M; i++){
				string[] line1 = Console.ReadLine().Split(' ');
				int Ai = int.Parse(line1[0]);
				int Bi = int.Parse(line1[1]);

				//より高くない方をtrueにする
				if(Hn[Ai-1] < Hn[Bi-1]){
						notGood[Ai-1] = true;
				}
				else if(Hn[Ai-1] > Hn[Bi-1]){
						notGood[Bi-1] = true;
				}
				//同じ高さの場合は、どちらもnotGood
				else{
						notGood[Ai-1] = true;
						notGood[Bi-1] = true;
				}
		}

		//カウント
		int cnt = 0;
		foreach(bool NG in notGood){
				if(!NG){
						cnt ++;
				}
		}

		Console.WriteLine(cnt);

	}
}