#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<ll> VL;
typedef vector<VL> VVL;
typedef pair<int, int> PII;

#define FOR(i, a, n) for (int i = (int)a; i < (int)n; ++i)
#define REP(i, n) FOR(i, 0, n)
#define ALL(x) x.begin(), x.end()
#define MOD 1000000007
#define INF 1000000000
#define PI 3.14159265359
#define EPS 1e-12

int main(void)
{
  int n;
  ll a, x[10];
  cin >> n >> a;
  REP(i, n) cin >> x[i];

  ll sum = 0;
  REP(i, n) sum += x[i];

  if(a*n == sum) cout << "YES" << endl;
  else cout << "NO" << endl;

  return 0;
}