#include<bits/stdc++.h>

using namespace std;
using ll=long long;
#define rep2(i, a, n) for(int i = (a); i < (n); i++)
#define rep(i, n) rep2(i,0,n)

int main(){
  cin.tie(nullptr);ios_base::sync_with_stdio(false);
  ll n,a,x;cin>>n>>a;
  ll hoge=0;
  rep(i,n){
    cin>>x;
    hoge+=x;
  }
  cout<<(hoge==a*n?"YES":"NO")<<endl;
}