#include <stdio.h>
#include <algorithm>
using namespace std;
using ll = long long;

int main() {
	ll n, a, x;
	scanf("%lld %lld", &n, &a);
	a *= n;
	for (int i = 0; i < n; i++) {
		scanf("%lld", &x);
		a -= x;
	}
	printf("%s\n", a ? "NO" : "YES");
}