#include<bits/stdc++.h>
#define REP(i,n) for(int i=0;i<(int)(n);i++)
using namespace std;
typedef long long int ll;
int main()
{
  ll n,a;
  cin >> n >> a;
  vector<ll> x(n);
  REP(i,n)cin >> x[i];
  ll sum = 0;
  REP(i,n)sum += x[i];
  if(sum % n != 0){
    cout << "NO" << endl;
    return 0;
  }
  sum = sum/n;
  cout << (a==sum ? "YES" : "NO") << endl;
  return 0;
}