#include <iostream>
using namespace std;

int main(){
	int n, a, sum = 0;
	cin >> n >> a;
	for(int i = 0; i < n; i++){
		int x;
		cin >> x;
		sum += x;
	}
	cout << (double(sum) / n == double(a) ? "YES" : "NO") << endl;
}