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