#include <stdio.h>

int main(void)
{
	int n;
	long a;
	long x[10] = {0};
	long total = 0;
	int i;

	scanf("%d %ld", &n, &a);
	for (i = 0; i < n; i++) {
		scanf("%ld", &x[i]);
		total += x[i];
	}

	if ((double)a == (double)total / n)
		printf("YES\n");
	else
		printf("NO\n");
	
	return 0;
}