#include <iostream>
#include <algorithm>
#include <cstring>
#include <string>
#include <vector>
#include <queue>
#include <deque>
#include <cmath>

#define AS(a) (sizeof(a)/sizeof(a[0]))
using namespace std;
long long int MOD = 1000000007;
long long int INF = 1000000007;


int main() {
  int n,a;
  cin >> n >> a;
  int x[n];
  for(int i = 0; i < n; i++) {
    cin >> x[i];
  }
  long long int sum = 0;
  for(int i = 0; i < n; i++) {
    sum += x[i];
  }
  if(sum % n != 0 || (sum / n) != a) cout << "NO" << endl;
  else cout << "YES" << endl;
}