#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;
typedef vector< pii > vp;
typedef vector< double > vd;
typedef vector< vd > vvd;
typedef vector< string > vs;

template< class T1, class T2 >
int upmin( T1 &x, T2 v ){
  if( x > v ){
    x = v;
    return 1;
  }
  return 0;
}

template< class T1, class T2 >
int upmax( T1 &x, T2 v ){
  if( x < v ){
    x = v;
    return 1;
  }
  return 0;
}

const int INF = 0x3f3f3f3f;

int N, A;
vi X;

void init(){
  cin >> N >> A;
  X = vi( N );
  for( int i = 0; i < N; ++i ){
    cin >> X[ i ];
  }
}

void preprocess(){
  ll s = 0;
  for( int i = 0; i < N; ++i ){
    s += X[ i ];
  }
  if( 1LL * N * A == s ){
    cout << "YES" << endl;
  } else{
    cout << "NO" << endl;
  }
}

void solve(){

}

signed main(){
  ios::sync_with_stdio( 0 );
  init();
  preprocess();
  solve();
  return 0;
}