#include <bits/stdc++.h>
#define FOR(i,a,b) for(int i = (a); i < (b); ++i)
#define REP(i,n) FOR(i,0,n)
#define SZ(n) (int)(n).size()
#define ALL(n) (n).begin(), (n).end()
using namespace std;
typedef long long LL;
typedef vector<int> VI;

int main() {
	int n, x[10];
	LL a, ans = 0;
	cin >> n >> a;
	REP(i, n) {
		cin >> x[i];
		ans += x[i];
	}
	cout << ((a * n == ans) ? "YES" : "NO") << endl;
	return 0;
}