#include <iostream>
using namespace std;
#define YES cout << "YES" << endl
#define NO cout << "NO" << endl

int main(void){
    int n, a, x;
    cin >> n >> a;
    long long sum = 0;
    for (int i = 0; i < n; i++) {
        cin >> x;
        sum += x;
    }
    (sum == n * a) ? YES : NO;
}