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