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)

use std::io::stdin;
use std::str::FromStr;
#[allow(dead_code, unused_mut)]
fn read<T: FromStr>() -> T {
    let mut s = String::new();
    stdin().read_line(&mut s).ok();
    s.trim().parse().ok().expect("1")
}
#[allow(dead_code, unused_mut)]
fn read_vec<T: FromStr>() -> Vec<T> {
    read::<String>()
        .split_whitespace()
        .map(|e| e.parse().ok().expect("2"))
        .collect()
}
#[allow(dead_code, unused_mut)]
fn read_two<T: FromStr>() -> (T, T) {
    let mut s = String::new();
    stdin().read_line(&mut s).unwrap();
    let mut x = s.split_whitespace().map(|x| x.parse().ok().unwrap());
    (x.next().unwrap(), x.next().unwrap())
}
#[allow(dead_code, unused_mut)]
fn read_three<T: FromStr>() -> (T, T, T) {
    let mut s = String::new();
    stdin().read_line(&mut s).unwrap();
    let mut x = s.split_whitespace().map(|x| x.parse().ok().unwrap());
    (x.next().unwrap(), x.next().unwrap(), x.next().unwrap())
}
#[allow(dead_code)]
fn remove_whitespace(s: &str) -> String {
    s.chars().filter(|c| !c.is_whitespace()).collect()
}

#[allow(unused_imports)]
use std::io::{stdout, Write};
#[allow(unused_imports)]
use std::collections::HashMap;
fn gcd(mut x: u64, mut y: u64) -> u64 {
    let mut z = x;
    let mut gcd_num = x;
    while z != 0 {
        gcd_num = z;
        z = y % x;
        y = x;
        x = z;
    }
    gcd_num
}
fn main() {
    let (n, m) = read_two::<usize>();
    let h: Vec<i32> = read_vec();
    let mut v: Vec<bool> = vec![true; n];
    for i in 0..m {
        let (a, b) = read_two::<usize>();
        if h[a - 1] > h[b - 1] {
            v[b - 1] = false;
        } else if h[a - 1] < h[b - 1] {
            v[a - 1] = false;
        } else {
            v[a - 1] = false;
            v[b - 1] = false;
        }
    }
    let a: Vec<bool> = v.into_iter().filter(|x| *x == true).collect();
    println!("{}", a.len());
}