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: Time Limit Exceeded)

package main

import "fmt"

func main() {
	var n, m int
	fmt.Scan(&n, &m)
	h := make([]int, n, n)
	a := make([]int, m, m)
	b := make([]int, m, m)
	for i := 0; i < n; i++ {
		fmt.Scan(&h[i])
	}
	for i := 0; i < m; i++ {
		fmt.Scan(&a[i], &b[i])
		a[i]--
		b[i]--
	}

	number := 0
	for i := 0; i < n; i++ {
		if isGood(m, i, h, a, b) {
			number++
		}
	}
	fmt.Println(number)

}

func isGood(m, at int, h, a, b []int) bool {
	for i := 0; i < m; i++ {
		if a[i] == at {
			if h[b[i]] >= h[at] {
				return false
			}
		} else if b[i] == at {
			if h[a[i]] >= h[at] {
				return false
			}
		}
	}
	return true
}