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 (Clang 10.0.0) (judge verdict: Runtime Error)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
typedef struct tagListNode {
  int H;     /* 高さ */
  int flag;	//goodなら1、badなら0
} SKY;

int main(void){
	SKY *S;
	int N,M,A,B;
	int i,ans;
	char str[100000];
 
	fgets(str, sizeof(str), stdin);
	N=atoi(strtok(str," "));
	M=atoi(strtok(NULL," "));

	S=(SKY*)calloc(N,sizeof(SKY));

	fgets(str, sizeof(str), stdin);
	S[0].H=atoi(strtok(str," "));
	S[0].flag=1;
	for(i=1;i<N;i++){
		S[i].H=atoi(strtok(NULL," "));
		S[i].flag=1;
	}

	for(i=0;i<M;i++){
		fgets(str, sizeof(str), stdin);
		A=atoi(strtok(str," "))-1;
		B=atoi(strtok(NULL," "))-1;
		if(S[A].H < S[B].H ){
			S[A].flag=0;
		}else{
			S[B].flag=0;
		}
	}

	ans=0;
	for(i=0;i<N;i++){
		if(S[i].flag == 1)ans++;
	}

	printf("%d\n",ans);

	free(S);

	return 0;
}