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: Runtime Error)

#include<stdio.h>
int main(){
    int n,m;
scanf("%d%d",&n,&m);
int elevation[n];
for(int i=0;i<n;i++){
    scanf("%d",&elevation[i]);
}
int a[n][n];
for(int i=0;i<n;i++){
    for(int j=0;j<n;j++){
        a[i][j]=0;
    }
}
int start,end;
for(int k=0;k<m;k++){
        scanf("%d%d",&start,&end);
        a[start][end]=1;
        a[end][start]=1;
}
int good_obs=0;
for(int i=0;i<n;i++){
    int flag1=0;
    int flag2=0;
    int j=0;
    while((j<n)&&((flag1==0)||( flag2==0))){
        if(a[i][j]==1){
            flag1=1;
        }
        if((elevation[j]>elevation[i])&&(a[i][j]==1)){
            flag2=1;
        }
        if((flag1==1)&&(flag2==1)){
            break;
        }
        j++;
    }
    if((flag1==0) || (flag2==0)){
            good_obs++;
    }
}
printf("%d",good_obs);
return 0;
}