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 Rust (1.42.0) (judge verdict: Accepted)

fn main() {
    let (n, m, v) = read();
    let ans = solve(v);
    write(ans);
}

#[derive(Debug)]
pub struct Tendodai {
    height: i32,
    rinsetsu: Vec<i32>,
}

fn read() -> (i32, i32, Vec<Tendodai>) {
    let mut l1 = String::new();
    std::io::stdin().read_line(&mut l1).ok();
    let mut iter = l1.trim().split_whitespace();
    let n = iter.next().unwrap().parse::<i32>().unwrap();
    let m = iter.next().unwrap().parse::<i32>().unwrap();

    let mut l2 = String::new();
    std::io::stdin().read_line(&mut l2).ok();
    let iter = l2.trim().split_whitespace();
    let mut v = Vec::<Tendodai>::new();
    for (i, h) in iter.enumerate() {
        let h = h.trim().parse::<i32>().unwrap();
        v.push(Tendodai{height: h, rinsetsu: Vec::<i32>::new(),});
    }

    for i in 0..m {
        let mut l1 = String::new();
        std::io::stdin().read_line(&mut l1).ok();
        let mut iter = l1.trim().split_whitespace();
        let a = iter.next().unwrap().parse::<i32>().unwrap();
        let b = iter.next().unwrap().parse::<i32>().unwrap();

        v[a as usize - 1].rinsetsu.push(b - 1);
        v[b as usize - 1].rinsetsu.push(a - 1);
    }

    (n, m, v)
}
 
fn write(x: i32) {
    println!("{}", x);
}
 
fn solve(v: Vec<Tendodai>) -> i32 {
    let mut count = 0; 
    for i in v.iter() {
        if i.rinsetsu.len() == 0 {
            count += 1;
        } else {
            if i.rinsetsu.iter().all(|&x| i.height > v[x as usize].height) {
                count += 1;
            }
        }
    }

    count
}