#include<bits/stdc++.h>
#define MOD 1000000007
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3f
#define EPS (1e-10)
#define rep(i,n)for(int i=0;i<(n);i++)
using namespace std;
typedef long long ll;
typedef pair<int, int>P;

int main() {
	int n, a; scanf("%d%d", &n, &a);
	double sum = 0;
	rep(i, n) {
		int x; cin >> x; sum += x;
	}
	puts((double)a == sum / n ? "YES" : "NO");
}