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: Wrong Answer)

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

    public class Program
    {
        public static void Main(string[] args)
        {
            new C().test();
        }
    }


	public class C
	{
		public void test()
		{
			// N人の社員
			var inputNM = CommonRead.ReadIntL();
			var inputH = CommonRead.ReadIntL();
			var inputA = new List<int>();
			var inputB = new List<int>();
			var inputAB = new List<List<int>>();

			for (var temp =0; temp< inputNM[1]; temp++)
			{
				var tem = CommonRead.ReadIntL();
				var min = tem.Min();
				var max = tem.Max();
				inputA.Add(min);
				inputB.Add(max);

				var ab = new List<int>();
				ab.Add(min);
				ab.Add(max);
				inputAB.Add(ab);
			}
			// 重複削除
			inputAB = inputAB.Distinct().ToList();

			// ここまで格納処理

			var groupSub = inputA.GroupBy(g => g)
			.Select(s => new { key = s.Key, value = s.Count() }).
			ToDictionary(d => d.key, d => d.value);


			// 計算に出た山の個数
			var unique = new List<int>();
			inputA.ForEach(i => unique.Add(i));
			inputB.ForEach(i => unique.Add(i));
			unique = unique.Distinct().ToList();

			var count = inputNM[0] - unique.Count();

			// グループ化個数繰り返す
			foreach(var key in  groupSub.Keys)
			{
				var j = 0;
				//計算
				foreach(var temp in inputAB.Where(s => s[0] == key))
				{
					j++;
					//以下だった場合はやめる
					if (inputH[temp[0] -1] <= inputH[temp[1]-1]) break;
					if (j > groupSub[key]) continue;

					count++;


				}
			}

			Console.WriteLine(count);


		}
	}

static class CommonRead
{
    public static string ReadStr()
    {
        return Console.ReadLine();
    }
    public static string[] ReadStrA()
    {
        return ReadStr().Split(' ');
    }
    public static List<string> ReadStrL()
    {
        return ReadStrA().ToList();
    }
    public static int ReadInt()
    {
        return Convert.ToInt32(ReadStr());
    }
    public static int[] ReadIntA()
    {
        return ReadStrA().Select(s => Convert.ToInt32(s)).ToArray();
    }
    public static List<int> ReadIntL()
    {
        return ReadStrA().Select(s => Convert.ToInt32(s)).ToList();
    }
    public static long ReadLong()
    {
        return Convert.ToInt64(ReadStr());
    }
    public static long[] ReadLongA()
    {
        return ReadStrA().Select(s => Convert.ToInt64(s)).ToArray();
    }
    public static List<long> ReadLongL()
    {
        return ReadStrA().Select(s => Convert.ToInt64(s)).ToList();
    }

    public static decimal ReadDecimal()
    {
        return Convert.ToDecimal(ReadStr());
    }
    public static decimal[] ReadDecimalA()
    {
        return ReadStrA().Select(s => Convert.ToDecimal(s)).ToArray();
    }
    public static List<decimal> ReadDecimalL()
    {
        return ReadStrA().Select(s => Convert.ToDecimal(s)).ToList();
    }

    public static double ReadDouble()
    {
        return Convert.ToDouble(ReadStr());
    }
    public static double[] ReadDoubleA()
    {
        return ReadStrA().Select(s => Convert.ToDouble(s)).ToArray();
    }
    public static List<double> ReadDoubleL()
    {
        return ReadStrA().Select(s => Convert.ToDouble(s)).ToList();
    }

}