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: Wrong Answer)

#include <iostream>
#include <vector>
using namespace std;
int main(){
  int n, m, h, ans;
  cin >> n >> m;
  vector<int> a(n);
  vector<vector<int> > c(n, vector<int>(2));
  for(int i=0;i<n;i++){
    cin >> a[i];
    c[i][0]=i;
    c[i][1]=1;
  }
  vector<vector<int> > b(m, vector<int>(2));
  for(int i=0;i<m;i++){
    for(int j=0;j<2;j++){
      cin >> b[i][j];
      b[i][j]--;
    }
  }
  for(int i=0;i<m;i++){
    if(a[b[i][0]] < a[b[i][1]]){
      c[b[i][0]][1] = -1;
    }else if(a[b[i][1]] < a[b[i][0]]){
      c[b[i][1]][1] = -1;
    }
  }
  ans = 0;
  for(int i=0;i<n;i++){
    if(c[i][1] == 1){
      ans++;
    }
  }
  cout << ans;
}