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 Go (1.14.1) (judge verdict: Accepted)

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

var sc = bufio.NewScanner(os.Stdin)

func nextInt() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}

	return i
}
func main() {
	sc.Split(bufio.ScanWords)
	n := nextInt()
	m := nextInt()
	hlist := make([]int, n+1)
	alist := make([]int, m+1)
	blist := make([]int, m+1)
	goodlist := make([]int, n+1)
	var i, omen int

	for i = 1; i <= n; i++ {
		hlist[i] = nextInt()
	}
	for i = 1; i <= m; i++ {
		alist[i] = nextInt()
		blist[i] = nextInt()
		//fmt.Println("hlist[alist[i]], hlist[blist[i]]", hlist[alist[i]], hlist[blist[i]])
		if hlist[alist[i]] <= hlist[blist[i]] {
			goodlist[alist[i]] = -1
		}
		if hlist[alist[i]] >= hlist[blist[i]] {
			goodlist[blist[i]] = -1
		}
	}

	//fmt.Println(goodlist)
	for i = 0; i <= n; i++ {
		if goodlist[i] == -1 {
			omen++
		}
	}
	fmt.Println(n - omen)
}