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