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-csc 3.5.0) (judge verdict: Accepted)

using System;
using System.Linq;
using System.Collections.Generic;
using System.IO;
using static System.Console;


namespace atcorder2
{
    class Program
    {
        public static long Read()
        {

            return long.Parse(Console.ReadLine());
        }

        public static long[] Reads()
        {
            return Console.ReadLine().Split().Select(long.Parse).ToArray();
        }

       
       
        public static long gcd(long x,long y)
        {
            if (x < y) gcd(y, x);
            
            while (y > 0)
            {
                var z = x % y;
                x = y;
                y = z;
            }
            return x;
        }

        public static long lcm(long x,long y)
        {
            return x * y / gcd(x, y);
        }



        static void Main(string[] args)
        {
            var sw = new StreamWriter(OpenStandardOutput()) { AutoFlush = false };
            SetOut(sw);


            var nm = Reads();
            var n = nm[0];
            var m = nm[1];
            var h = Reads();
            var ans = new bool[n];
            var a = new long[n];
            var b = new long[n];
            for (int i = 0; i <m ; i++)
            {
                var ab = Reads();
                if (h[ab[0]-1] > h[ab[1]-1]) ans[ab[1] - 1] = true;
                else if (h[ab[0]-1] < h[ab[1]-1]) ans[ab[0]-1] = true;
                else
                {
                    ans[ab[0]-1] = true;
                    ans[ab[1]-1] = true;
                }
            }
            long res = 0;
            for (int i = 0; i < n; i++)
            {
                if (!ans[i]) res++;
            }
            WriteLine(res);

           
          
            Out.Flush();
        }
    }
}