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