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++ (GCC 9.2.1) (judge verdict: Accepted)

#include<bits/stdc++.h>
using namespace std;
int main(){
    long long n,m;
    cin >> n >> m;
    long long h[n];
    for (long long i = 0; i < n; i++){
        cin >> h[i];
    }
    long long a[m],b[m];
    for (long long i = 0; i < m; i++){
        cin >> a[i] >> b[i];
    }
    long long mark[n] = {};
    for (long long i = 0; i < m; i++){
        //cout << h[a[i] -1] << h[b[i]-1] << endl;

        if (h[a[i]-1] > h[b[i]-1]){
            mark[b[i]-1] = 1; //1だと必ず、良い展望台じゃない
        }else if (h[a[i]-1] < h[b[i]-1]){
            mark[a[i]-1] = 1;
        }else{
            mark[a[i]-1] = 1;
            mark[b[i]-1] = 1;
        }
    }
    long long count = 0;
    for (long long i = 0; i < n; i++){
        //cout << mark[i] << endl;
        if (mark[i] != 1){
            count++;
        }
    }
    cout << count <<endl;
    //cout << 1.0 * clock() / CLOCKS_PER_SEC;
    return 0;
}