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.Linq;
using System.Collections.Generic;

namespace atcoder.abc166.c
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] paramArray = getIntParams();
            int N = paramArray[0];
            int M = paramArray[1];

            int[] H = getIntParams();

            List<int>[] route = new List<int>[N + 1];
            for (int c = 0; c <= N; c++)
            {
                route[c] = new List<int>();
            }

            for (int i = 1; i <= M; i++)
            {
                int[] data = getIntParams();
                int A = data[0];
                int B = data[1];

                if (!route[A].Contains(B))
                {
                    route[A].Add(B);
                }
                if (!route[B].Contains(A))
                {
                    route[B].Add(A);
                }
            }

            int ret = 0;
            for (int x = 1; x <= N; x++)
            {
                if (route[x].Count == 0)
                {
                    ret++;
                }
                else
                {
                    int err = 0;
                    for (int y = 0; y < route[x].Count; y++)
                    {
                        if (H[x - 1] <= H[route[x][y] - 1])
                        {
                            err++;
                        }
                    }
                    if (err == 0)
                    {
                        ret++;
                    }
                }
            }
            Console.WriteLine(ret);
        }
        static int getIntParam()
        {
            return int.Parse(Console.ReadLine());
        }
        static int[] getIntParams()
        {
            return Console.ReadLine().Split(' ').Select(i => int.Parse(i)).ToArray();
        }
        static long getLongParam()
        {
            return long.Parse(Console.ReadLine());
        }
        static long[] getLongParams()
        {
            return Console.ReadLine().Split(' ').Select(i => long.Parse(i)).ToArray();
        }
        static string getStringParam()
        {
            return Console.ReadLine();
        }
        static string[] getStringParams()
        {
            return Console.ReadLine().Split(' ');
        }
        static decimal getDecimalParam()
        {
            return decimal.Parse(Console.ReadLine());
        }
        static decimal[] getDecimalParams()
        {
            return Console.ReadLine().Split(' ').Select(i => decimal.Parse(i)).ToArray();
        }
    }
}